5700LE/Overclock/denied

[drwngflies]

I am new to this forum, and first would like to thank those who help us(newbies) out. Yes, I did search for related topics before submitting this thread, and tried "fixes" first. So, here goes:
I have a Systemax PC:Biostar P4M266A M/B,bus clock@100Mhz, 2.0Ghz Celeron chip, 256MB installed RAM, added 512MB DDR RAM, and running W/XP/SP2, along with nVidia's 5700LE, Direct X-9.
I have ben having stop (blue) screen errors showing my old (nVidia) driver at fault. I searched forums to try to resolve the issue, to no avail. I tried the 71.84 driver earlier today, and then removed it and tried the 66.93 . I am not having errors yet, but time will tell.
I wish to O/C my card, and installed Riva to do so. My stock settings are: (2-D) 225.0 core, and 199.5 mem.
(3-D) 250.0 core, and 400.0 mem
When I try to move them up 2 points, and do internal test, it fails and won't let me save. Am I not enabling something first to be able to reset the speeds? ( Newbie)
Thanks for the opportunity to ask those in knowledge, for I know nothing,. . .yet.
If you can stop laughing at my setup long enough to type, thnx.