Don't throw out that sluggish PC. Give it a tune-up!
A fine-tuned Windows XP PC can run quite fast even it's seriously lacking in the memory and CPU department. Before you chuck out your PC to buy a new one, try stripping some of the rust that's built-up over the years; the results may surprise you.
It's probably your operating system that's slow, not the PC. It's software, not hardware - you know, invisible 1s and 0s held in an electric field representing your data. Your computer is still fast, but there's a ton of stuff slowing it down.
Read full article on how to speed up your PC: Tweak3D.net - Windows XP 15 Minute Tune-Up