Try running CCleaner as well, it removes temp files and such, but I have also seen it fix profile issues and problems with leftover applications, via running the registry cleaner.

Malwarebytes is really solid for picking up things that Adaware might miss.

Also, check the size of your profile, a large profile can make XP run really slow.

If you have slow load times for apps, look for a dead shortcut on the Desktop, that could really cause speed issues as well.

You might want to turn off indexing, right click on the HDD>properties uncheck it and then when prompted, ignore all. That helps speed up a little.

How much RAM you got? If it's 512 or lower, you should add more.

Maybe put your install disk in and the run "sfc /scannow" to repair system files.