For my instane, I went from a 9700 Pro to a 6800GT.
Though the difference was huge, including double points in 3dmark03, my favorite game in particular Rome:Total War showed little difference at all because the game is so cpu dependant. Yes, the graphics looked better, but performance wasnt much different.
One thing you said was you "plopped" it in. No video card will work good if you just plop it in.
Let me give you an example... WHen I got my 9700 pro back in the day I plopped it in, never uninstalling the previous drivers. It doesnt matter if in your case youre coming from another Nvidia card, you MUST uninstall ALL drivers. You must then do the safe mode procedure to uninstall using driver cleaner.
Download the latest nvidia drivers and then install them...
The 6800 is lacking in speed and pipelines compared to its bigger brothers, but you should notice a good increase because there are other technologies there much better than the FX5600.
<font color=red> And the sign says "You got to have a membership card to get inside" Huh
So I got me a pen and paper And I made up my own little sign </font color=red>
ok, I "plopped" in the Opteron 148 I got yesterday and got a 3D Mark score of 9400. I guess I can see some improvement in Star Wars Galaxies, but definitely not a good as I was hoping for. I still can't turn on shadows in the game and keep the frame rate smoothe...