GTA IV for Windows is a very demanding game even for high-end gaming machines. Also, it only runs well if you have a quad-core processor - that's right, even a very fast dual core won't run it well at all, but a quad can handle it just fine. Of course, you also need a GeForce 8800-, 9800-, or GTX-class card (a Radeon 38xx or 48xx will also do the job). And I doubt Cider would do very well playing the game.
In other words, unless you have a Mac Pro with an upgraded video card or a high-end gaming PC, you're not going to be able to play it. Get it for one of the consoles.