yes, a 4850 will be faster than a 9600 gso, i have a 9600 gso too and from experience i would bet that the 4850 has more power

Guess that depends on the price. Here in Austria that model ships around 185 Euros or 253 Dollars. Not sure why it is that expensive. I can get the 4890 for the same price or the 5770 XT.
Upgrading to the HD4850 will be a big step regarding performance. I have the HD3850 and I am still able to play modern video games at mid to high settings fairly well. The 4850 is a lot faster than mine and mine is a lot faster than yours so I think you get the picture.

So if you can get it at a decent price than yes it will be definitely better for gaming. Otherwise you might take a look at new HD5 series or, if DX11 is not important, the GeForce GTS/X series.

Btw. your screen's resolution is 1280 by 720 pixels - any modern mid-range and higher video card should be able to handle it with AA and AF turned on. The 9600GSO is definitely "low"-range or low-budget and from what I've seen in my friends Dell PC, very slow. Now he has an older 8800GT and it is way faster and is not that loud every time you turn the PC on.

I suggest you forget about the HD4850 and get the new HD 5770 which has Direct X 11.

Don't buy now, wait till the GTX400 series from Nvidia are released, then all the HD5000 series from ATi will have their prices dropped. Then, its a good chance to get a HD5850. Its worth it. The 5850 is a killer.

get either a 5750 or a 5770 they dx11

don't get pre-overclocked cards do it yourself it takes a bit of research and hours but its worth it

defenetly the HD5770, supports DX11 and its all new and uptodate, plus its very fast comperd to the 5750

It takes about 5-10 seconds to OC a card and maybe one one page artile-OCing gpu's is just absurdely ez

I agree with the 5770, it has DX11 and probably better power management >>; and 5850 if you're willing to dip your wallet even further.

hi thank you ppl for your help i got the hd 4850 for about $100 its a real good performance card iv been blown away lol i took my old card and overclocked the hell out of it till it give in and went to gpu heaven it was fun but i will be getting a 5770 once iv seen wot fermi has to offer the 4850 will keep me going for now i can allways sell later...