I have the slight feeling that we are dealing with a troll.
But if the question is serious, let'S be honest:
Your system isn't even enough for GTA 4, how did you expect to run GTA 5 on it at all.
You should be able to run Crysis (the first in the series!) quite well, but anything newer should be pretty much impossible with that system.
As fur upgrades: Depending on your systems and location you could get a Core 2 Quad for somewhere around $40-80 and 2x 2 GB DDR2 RAM for around $20-30, double the ram, put a decent cooler on it and overclock it hard and you should be somewhere around half the performance of a recent entry Core i5.
(A Q6600 would already be atleast around 6x as fast as your current chip, just for comparison.