Hi Adam:
What I do usually is go to eBay and purchase a top-of-the-line "barebone computer" for about $300 which upgrades my motherboard, ram memory, and gets me a new case. I use the HD as a backup drive and buy a new HD too. I reuse the CD/DVD drive. Not a bad deal.
Sometimes the Dells/Gateways offer good new computers for about $500. You can donate your computer to Goodwill in that case.
But 3 years is not that old...
Cheers,
Al