4 year old work computer, no video card, 1gb ram:
This 4 year old HP is one of the best computers i've owned. No problems, it's fast still (mainly because I take pretty good care of it), the power supply went in it last year, but no big deal. The PSU's that come with these desktops are crap anyway. This computer does everything I need to do for work, and I only miss the video card when I'm doing some photoshop or opening a solidworks file, which is not very often.
I firmly believe keeping a well organized and clean computer can last someone years and years. Unless you're doing gaming, major editing, or engineering or something that requires a lot of ram/video processing power, a cheap machine like this one is perfect for 90% of users out there who check email and surf the web.