Ram

OK,so i have had my computer
for over a year now and it was working like a dream but now im starting to get lots of errors. My frequent errors are BSOD's, program crashes, installing windows xp error while at the setup menu and many more frequent errors during installation of windows. I tried running on two different hard drives and each of them have been giving me problems but this hard drive my Maxtor 300 gigabyte hard drive actually made it through the install but now im having errors with programs such as when installing games they will crash or say that the server is busy and what not but i have tested some of my parts such as the video card, the power box, the CD rom and everything else except the hard drive, the ram, and the mobo because i know im getting errors from one of those three which is why im hear to find out what is corrupting my windows.