Well, there's no reason the sound effects couldn't be of the same or similar quality - they're just sounds. The only real limit there is the memory we want to devote to them in the game - and most sounds aren't particuarly large.
As for the imagery itself...if will depend on what kind of system you're packing. Anything with at least a reasonable processor and a gig of ram should be fine. To get the really shiney stuff, you'll probably need a video card that supports Shader Model 2.0 or above. By the time this game sees the light of day those will be fairly cheap - under $50, most likely.
Even with the best possible system you'll still not be hitting quite as close to the pre-rendered versions as you might hope. I suspect you won't be able to tell, though. The game will be played at a much higher frame rate, and a much higher resolution - this helps cancel out some of the negitive effects of the lower-quality models..