i don't think a 4770 is gonna cut it for a 24" monitor running games like cod mw2 at high settings.... my budget right now is $250 max.
and i don't have a small desktop case either. dimensions for my tower is 18cm wide, 42cm tall, and 45cm long. of course if were talking about just the usable area, then my case can fit at max a graphic card thats 28-30cm. anymore longer and it will scrap against the case or other wirings.
The 4770 will run cod mw2 @ high settings. My 8800gt ran it @ mostly high @ 1600x1200.
My 9800gt runs it @ high easily.
As far as I know the 4770 is the smallest highest performing card.
Mabe a 5750? It's faster then a 4850 and has 1gb memory for higher res?
Edit:
The 5770 is 8.5 inches (21.5 cm) and the 5750 is 7 inches =(17.78 cm).
So the 5750 is the new smallest fastest card.
Wait! you have 24cm? That changes everything. I thought you said the 5770 would not fit?
A 5850 I believe is 24cm, but that to much card for your cpu! Go with a 5770.