Oh well... I have a computer what is almost exactly like the one what is recommended. CPU is just a Athlon x2 with 2.4Ghz.
And it runs like shit. Well ok it's playable, but a bit annoying.
BTW I have been thinking, why the Minimum AMD processor is X2 64 2.4Ghz and recommended is Phenom X3 2.1Ghz. Wouldn't the X2 with higher clock rate perform better than X3 with lower clock rate? I don't think GTA IV is able to fully use all the performance of the three cores?