First, open the computer tower case and use compressed air to blow out the dust and junk from around the processor, then heatsink, the power supply, all vents and all fans.
Next, hopefully you are aware that McAfee Security Suite is a major resource hog.. It's your choice, but try temporarily uninstalling the entire suite and I'll bet your performance increase is noticeable.. There are other options if you choose to move to other antivirus/antispyware programs. On the other hand, if you want to keep McAfee running, then I'll recommend kicking up your RAM to at least 1 GB.
Next, click on the link below and follow all of the procedures to check for malware, delete junk files, and disable the unnecessary startup programs and services. It may take quite a while to perform all the steps, but it should help substantially.:
Hope this helps.
My 5+ year old Dell Dimension 4600 is slowing down overtime. It reacts slower and slower to requests. I bought it used for a friend a few years back and it responded much faster back then.
It's got: Pentium 4 2.8ghz processor
160 Hard drive (maybe more?)
McAfee Security Suite 2009
I am only using 25% of the hard drive storage capacity.
Everytime it changes from one page to another, there is a few second delay and then part of the old page and part of the new page are shown at the same time. It can take several seconds for the new page to fully show itself.
I do not think that the problem is associated with my DSL subscription because this condition is present even when I am offline.