9 Series aren't really any different to the 8 series. An 8800 would probably, misleadingly so, outperform a 9600 (it'd have to be 8800GT and 9600GT, for example.), but that doesn't stop the 9600 being a good card. The lower level 9 series are astonishingly cheap, too, but will still haul a steady framerate on max in most games (i get a constant 50 something in COD4, max, at 1680x1050).
The point i also want to make is you don't NEED a 9800GTX. Unless you're planning to run a 40" plasma screen or some balls like that then there simply is NO NEED.
My advice: The 8800 is still the definitive card on the market, getting cheap now, And you won't need anything more unless you plan to go past a 26 or something + inch screen.