Yes I will...... cause I dont got a console for GTA4  
but once it  comes for the pc... im not sure  
 im not sure when it comes out for pc though
If and when it does come out for PC, you'll probably need a DX10 graphics card, 2gigs of ram and a 3ghz core2duo pentium... which counts me out 
Rest assured that's very unlikely to be the case.
i sure as dangit hope you're right!
It would be a stupid move (stupid doesn't cut it, really) to use DX10 exclusively.
2 GB of RAM is becoming more and more "standard", you'll need it eventually, not that it's a problem, look at RAM prices if you haven't, you can get 4 GB RAM for €60 over here!
There's no such thing as a Core 2 Duo Pentium 

All in all, should you need to upgrade (most likely RAM), it will not kill you off.