What planet are you on? For $20 you get a card that runs cooler, has PhysX and Cuda, and performs better in some games. For $20 more. It's certainly not a horrible card, it's got just as much value as the 4850, it's just preference as to whether you want PhysX/Cuda or not.
The difference is more like $40.
CUDA is useless to most gamers. The only time I ever see it being used is with folding. PhysX is still limited to an extremely small number of games, so that is not much of a deciding factor.
The GTS 250 does not run cooler in most cases. Most all the 4850s left are non-reference and have much better coolers than the reference model. They also have voltage control (at least, most do) so overclocking is better.
I only mentioned the 4850 because it has identical performance to the GTS 250. The really good value is a 5750, which will perform close to a GTX 260, or a 5770, which is now about the same as a 280. They also have DX11, openCL, SM5, etc.
Basically, ATI has nVIDIA beat in pretty much every way right now.
The GTS 250 ~ HD 4850 ~ HD 5750 all perform alike, anyone who argues otherwise is just beating a dead horse.
Rerun the tests with Catalyst 10.3 and the 5750 will be more like a GTX 260. The 4850 also gets a nice boost in a couple of games, but nothing too significant.
Anything else special I need to know with PSUs? The one I have came with my case so I didn't learn anything about them.
Time for a new PSU then. Never use the ones inluded with a case. they are always horrible quality.
What model is it?