This is a ridiculous debate. The Nvidiots are winning because they are outnumbering everyone else.
Lets put things into perspective.
1. the 4830 is faster. deal with it. the benchmarks that show otherwise had cards with disabled shaders and everyone knows that.
2. The only 2 games that the 9800gt beat it was Crysis and Oblivion. That's hardly a reason to pick it.
3. It's common knowledge that Nvidia got Crytek to "optimize" Crysis for their cards, so it is an invalid form of benchmarking.
4. G92s are faulty and Nvidia has already said so, after it was found out that they tried to cover it up. You would be nuts to buy a card that is known to be faulty.
5. Very few games use physX. Wiki has a long list, but it also has a disclaimer that states that many PhysX games don't support Nvidia PhysX.
6. And Finally very few people fold, and even fewer gpu fold. You can only use folding as a reason if the person you are consulting has already stated that they fold. When I recommend parts to people if they dont fold then I consider it a non issue. This is an unbiased posture.
I'm sorry but I care to much to let the OP get screwed over. I'm the "bulldog" for a reason.
