[dsio]

The biggest change in the 91.33 driver is that it lets you overclock more. All of us on Geforce 6/7 cards have seen an improvement in overclocking since these 9x.xx series drivers.

Aside from that, try using the old control panel, its much easier. Are you using the standard ones, or the Xtreme-G modified ones?

And yes, the differences are subtle, but you notice them after a long time using the card. The 8x.xx series for example improved sharpness, and the 9x.xx series make the colours a bit more vibrant, while also applying a colour cycling effect to fog / smoke to make it look slightly more realistic.