Happy results. I upgraded my GeForce 5200 to a 7600 GS AGP w/ 512 meg memory, running on an HP Dual Core Pentium 4 w/ 2 Gb main memory, Kubuntu 8.04 w/ all updates including nvidia new driver.
Swapped the old card for the new, no other changes Worked wonderfully. Running 1.20 - I was able to select Ultra graphics setting and the client handled it perfectly. Admittedly, distant objects didn't paint right away, particularly in a crowded environment, but I experienced no significant lag and didn't crash.
One sour note: 1.21 doesn't work for me - won't even start a window - may re-install. But 1.18 and 1.20 run quite well for me.
Thanks for all the help/suggestions/comments.
UPDATE:
Well, not quite what I said - turns out that Kubuntu decided that I didn't need the nvidia new driver - it reverted to the nv driver - even so, it works, and as the saying goes, what's not broke, don't fix. I may try the closed driver later, but for right now, I'm a happy guy.
Second UPDATE:
1.21, after a re-install, works perfectly as well.
Third UPDATE:
Well... turns out that *something* rewrote my xorg.conf file - and while Kubuntu reported I was running nv, it was in fact running the new nvidiia driver - after a cold-restart, the effectively empty xorg.conf file resulted in a low-res desktop... Recovered with a backed-up xorg, which DOES run the restricted nvidia driver, and all is now well.
Still wonder why I sometimes loose my xorg.conf file - that's the reason I back it up so carefully - not the first time it's been overwritten.