You need more than one anti-spyware tool. Spybot S&D is okay in my opinion, but the more guns you have the better. http://www.superantispyware.com/superantispywarefreevspro.html is a great app that takes care of a lot of problems I've come across. The free version is all you need, look for the blue button on the bottom, install that and run it.

Also, adaware is good too. http://www.lavasoft.com/single/trialpay.php

If you have some cash though, you could always take your computer to a local store and have them wipe it clean and backup and restore all your data. Mainstream places like bestbuy are a little more expensive, a small local computer shop could do it for under $200 TOPS. Another option, if there is a local university or high school with a computer science department, there are usually more than enough geeks that would be willing to do that tasks for you for super cheap. That's how I made money back in those days :) I would email the Deans/Professors of those departments or see if there is a computer help desk you can call.

Heck ya! Get that LAMP box set. Linux has come a LOOOONG way. Dont know about using Red Hat though, try out Ubuntu. If you really want to learn how to operate in linux though, check out Gentoo. I guarantee you that would be an adventure.

Overclocking probably wont fix your problem. Usually when you do that you are messing with some really technical things deep down in your computer. How old is your computer? What are the specs on it?

Many times, spyware/malware will slow things down. That could be an issue.

I second cbchdude, you shouldn't have any problems running this on a Windows PHP MySQL stack.