I don't your level of expertise so I don't want to sound condescending. From your post it appears you did what most would think of first. However if you haven't cleaned your cache or run a disk cleaning program (ccleaner is a good one,) or one of many utility suites you can download for free, a registry cleaner, unistalled any old programs you don't use (you can always zip the executable for installation at a later time if you change your mind,) temp files, etc.

Also clear any old restore points as they use space for each one set, either manually or system set. If everything is running good now, just slow, open the control panel, click system, then the restore tab and check the box next to "turn off system restore," that will clear all restore points. Uncheck it and then set a new restore point. You can alway check it by clicking on "restore to an earlier time" to be sure it's clean. Date boxes that are bold are restore point, you can even manually delete them from there. Just be sure to turn the system restore back on and set a new point! If you aren't sure, leave it alone!

With every software program you install and uninstall, there are always junk files left behind, spyware and adware will all contribute to a bottle-neck as will a wrong configuration of your system. Additionally, while many people think that unistalling a program will also clean the registry of all remnants, it's not true. Not only that but with every installation, the registry expands; the problem is when you unistall, it doesn't shrink down to free space. It just bloats with junk which will slow you down.

WARNING: Do not delete anything you aren't sure of! It is best to leave it alone until you know what it is! This is very important, you could delete a critical file. Also either backup or set a restore point before doing any of this!!!!!

Also run "chkdsk /f" (without quotes: I use the following syntax, it takes a bit more time, but I think is worth it. At the C:\prompt type: chkdsk /f /r /v) the/f and /r are basically the same as they fix problems found on your disk if any, and the /v verifies the data has been written to disk correctly) at the dos prompt to check the disk for any errors or bad clusters which will corrupt files if they are occupying that space.

Check for updates for any drivers you may have installed and program updates as well. Being on a dial-up, you should use the Windows update site to get any security, program updates etc. You will be offered SP3, I would hold up on that for a little while longer - give them more time to work out the kinks (there are plenty of them) so do not use the automatic install, use the custom and you can choose what you want installed instead of what MS wants to.

After cleaning, run a defragger on the HD and the registry.

Only use one firewall and one anti-virus (kept up to date, whether it auto-updates or you have to do it manually) - using two or more thinking it keeps you more secure is a no-no. They will only work against each other. Use as many spyware or adware programs as you want. A monitoring program whether it is a stand-alone or part of your firewall or AV is a good idea to keep intrusions out. They will warn you and if you don't recognize the intruder, keep it blocked until you can find out exactly what it is.

Hope this helps you out, and if you were already knowledgeable of my suggestions, I apologize, but as I said, not knowing your level of expertise, I wanted to give you as much information as possible and I could think of at this time!

Good luck!