A few thoughts of mine on the subject...
Technically you could say that viruses/worms/trojans fall under the malware category, but who cares? The distinction is kind of a pointless one by and large if you ask me. All of them are unwanted.
That all being said, it should be mentioned that following some simple rules/conventions that are really pretty basic common sense type things, there is next to no need for the anti-malware/spyware programs. If one takes a good honest look at the situation, you see that only a few programs are responsible for the overwhelming majority of malware/spyware, and those programs just happen to be distributed by the same company. If you take a detached view of things, the answer is really pretty simple: Don't use these problematic programs. What could be simpler?
The problem with that comes in when people start developing emotional attachments to programs, or even specific companies. Never will anyone be able to explain to my satisfaction the whole Ford vs. Chevy argument. Maybe it's because I see a car as a way for me to get from Point A to Point B, not some substitute for my perceived lack of sexual prowess. A Ferrari might look really nice compared to a Pinto, but when my primary concern is say getting to work every day... The Ferrari just doesn't really have anything particularly compelling over the Pinto, unless maybe I'm chronically late, and going from 0-60 in under 10 seconds is particularly useful. But even then, it strikes me that I should be working more on getting out the door sooner, not getting some really fast car.
The same, IMO, should be said about computer programs. There's really very little that MS Word can do that WordPerfect or OpenOffice Writer can't do. All the features Microsoft loves to talk about Word having over the other word processors out there really doesn't mean much when the majority of people don't need anything more complex than WordPad. Assuming you're not into desktop publishing or anything like that, when's the last time you needed more than to be able to bold, italicize, or underline a few odd words in a document? Maybe change the font face and size. Bulleted lists are nice, but let's be honest, a simple asterisk will do just as well. If people simply looked at these as tools for getting a particular job done, this would be self-evident.
So moving along... If one takes a detached and objective view of the whole spyware/malware situation, you quickly see that Internet Explorer is the far and away offender. No other program even comes close. At a distant second is probably file sharing, or P2P, programs. Rounding out the hall of shame would be Outlook and Outlook Express, along with Windows Media Player, MSN/Windows Live Messenger, and the rest of the Office suite.
The logical solution is to simply avoid using these programs. There are alternatives for each and every one of them -- besides the file sharing programs -- that lacks the problem with spyware/malware. You can debate the reasons why these programs lack the same significant problems as the ones already mentioned, but that's all besides the main point: They don't have this problem now. Whether or not they will at some point in the future is at some point in the future. Today, right now, they are not plagued by these problems. So if they are otherwise equal in every important way, does it not seem foolish to be using anything else? If at some point they become afflicted like Microsoft's programs, there will likely be other alternatives that have cropped up and you can simply move on. It may be a hassle to learn a new program, but it's surely a much greater hassle to have to constantly be playing cleanup after these programs.
That's my reasoning for the tips I'll be leaving at the end of this post. However, I want to take a brief moment to address some questions I don't recall seeing anyone having had addressed when I started this message.
Anti-virus programs, as a general rule, do NOT detect spyware/malware at all. SOME AV programs do scan for malware as well, like later versions of Norton AV. However it's usually a token effort at best, and you're much better served by other free tools.
Further, the malicious software removal tool has got to be one of the single most useless things I've ever seen Microsoft distribute. I don't even bother with wasting my time downloading it anymore. It's NOT the same as Windows Defender, which started out life as a program known as GIANT Anti-Spyware. Then a few years ago Microsoft bought it and renamed it. First it was something like Windows anti-spyware, then it changed to Windows Defender. I personally find it a little suspect that Windows needs a defender product, for the reasons I outlined above. Mac and Linux users enjoy a rather carefree life not having to run AV or anti-spyware/malware programs, so what is it about Windows that causes it such difficulties? For my money, it can't simply be a function of its popularity, because despite the significant gains both the Mac and Linux platforms have made against Windows, the amount of viruses and spyware for both has remained pretty flat, while despite it's decreased popularity, growth of viruses and spyware/malware for Windows has exploded.
I'll also say that Norton AV is a bit of a resource hog. It's not as bad as McAfee VirusScan, but it's bad enough. So, when your current subscription runs out, or Symantec stops producing updates for it, I would consider making the switch to either AVG Free or Avast. I personally like AVG Free better, since I don't really look at my AV program enough to care if it has a skinnable interface like Avast loves to trumpet, and you don't have to register your copy of AVG Free every so often to keep it functioning. However, both are quite capable AV programs that are free of charge, and will generally consume much less in the way of resources than Norton AV. They also don't have the false-positive problem Norton AV is infamous for.
Also, if you doubled the amount of RAM you had in your system, you would likely see a marked performance increase.
So, with all that said, without further adieu the promised tips for keeping a well running machine.
TIPS FOR A SMOOTH RUNNING SYSTEM
The more of these suggestions you follow, the fewer problems you should have. Follow them all, and you've probably eliminated at least 95% of all potential problem sources.
Things you should NOT do
1: Use Internet Explorer
2: Use any browser based on Internet Explorer
3: Use Outlook or Outlook Express
4: Open email attachments you haven't manually scanned with your virus scanner
5: Open email attachments you were not expecting, no matter who they appear to be from
6: Respond to spam messages, including using unsubscribe links
7: Visit questionable websites (e.g. porn, warez, hacking)
8: Poke unnecessary holes in your firewall by clicking "Allow" every time some program requests access to the Internet
9: Click directly on links in email messages
10: Use file sharing or P2P programs
11: Use pirated programs
Things you SHOULD do
1: Use a non-IE or IE based browser
2: Always have an up to date virus scanner running
3: Always have a firewall running
4: Install all the latest security updates (the exception to the no-IE rule)
5: Delete all unsolicited emails containing attachments without reading
6: Manually scan all email attachments with your virus scanner, regardless of whether it's supposed to be done automatically
7: Copy and paste URLs from email messages into your web browser
8: Inspect links copied and pasted into your web browser to ensure they don't seem to contain a second/different address