Check the FAQ at the top of the forum Gino...it needs some cleaning up (I'm doing this right now), but it has some good information from the posters here.
As state din the FAQ, keep in mind that the FAQ consists of forum members'
opinions, based on their personal experiences.
Also note the current issue of FSM has a very good article on buying your first airbrush (they focus mainly on sub $80 brushes.
I'd point out the Tamiya set...it is a very good deal for an airbrush/compressor combo.
I might also point out that once you use an airbrush, you'll probably never touch a brush again for major paint jobs! An airbrush is pretty easy to get acquianted-with, the exception being the Dual-Action (they require a bit more finesse).
I model just about anything, including a massive Warhammer 40k army I'm building...base/final coats are always airbrushed. Results are always stunning.