toxicTom: Except for PC 3D games... From what I've seen of GTA4 on a (much more powerful machine than mine) friend's machine they must have ported it to Java2. Ot the GTA4.exe is in reality a PS3-Emulator for future hardware generations...
Even if it wasn't for all that DRM crap attached, I would certainly wait for reviews and performance tests before trying GTA5.
I agree GTA 4 could be more worked for PC, however, Rockstar has been honest admitting several times that PC market is not their target, being consoles the ones they work for. Besides, the similarity between actual consoles generation with a PC will make that conversion lot more easier and somehow, the game will take advantage of machine resources more efficient. Or that is what I expect.
I tested GTA 4 and Liberty Episodes once on my machine and it ran very well at mid settings. My machine is not a high ended one (AMD A8 3510mx, 8GB RAM 1366 Mhz, AMD HD 6620g, Windows 7 x64) so is obvious GTA 5 will not run so nice even at low low settings ):
Even that way, GTA 4 runs better than lots of Ubi PC "games". Sorry, I just hate Ubisoft since I don't understand why people like so much those low ended games.