I ended up just ordering new parts for my Stepmom. I'll be building her a fresh computer, and it's only costing $234USD after shipping is factored in. It'll be a pretty nice system, toting an AMD dual-core 2.3GHz processor, 1GB of ram, and an 80GB harddrive (it's plenty of space, trust me). I'm actually pretty excited to put it together and have her give it a test run, just to see how she likes her new-found speed.
I can only look back on my most recent upgrade which ended up costing me around $800USD. Since it was a few year ago, quality:cost ratio has gone way up, meaning the consumer gets a ton more bang for their buck. I can only imagine when quad-core will be the new standard for building a machine.
Oh man... I really hope that I don't become one of those crotchety old guys that shakes their fist at technological advances. "Those darned kids and their atomic processors! Why back in my day..."