Let's back up. What error are you getting?
Try winamp (
http://www.winamp.com). I'm willing to bet that this will fix all problems. It ran on my Win95, 32 MB RAM, 200 MHz computer pretty well, so I can guarentee that it will work on your computer. It is free, and a whole lot better than WMP. If it doesn't read your disks and play them well, my bet is on your CD Drive having a major error.