Computer help: I have done it all and computer still slow

IE8

I should probably chime in here even though I'm now a Mac-user. A friend of mine also got IE8 (through no real fault of his own - it seems if you're not vigilant WAU will install it by default) and then had untold problems with his XP-Pro SP3 system, Dell computer. To make a long story short(er) I got his IE7 back, cleaned up a few things using CCleaner first and then Glary Utilities, and then defragmented (both) his drives. He's now good to go, for however long that lasts...