reinstall Win2k? or change some settings?

i have win2k on a rather outdated machine. i am thinkiing about reinstalling Win2k. but if i do that i don';t have the Graphics card install software, i think it' an nVidia MX440 32MB card. nothing spectactular. like i said outdated machine. but after about 20-30 minutes of me having the machine on it seems to shut the monitor off and there is no way to "wake" it up. i went in thru display properties and made sure that the HDD never turned off and the Monitor never turned off. but even after that it seems that it just goes to sleep. and even while i am using the machine not just when it is idle. hibernate is not enabled so i know that's not it.

so thanks in advance