The pressue packs are rubbish.. do yourselves a favour and forget them.
As you use them they freeze on the outside and so pressure out drops to a point where nothing comes through the brush. You then have to sit the can in the sun to warm up and pressure to rise again... these are really bloody irritating pieces of crap to use.

Basic rule of a compressor for airbrush is to have too much air. I had a 2.5hp $99 compressor from supa Cheap and as Homepin states.. you bleed off very little to your airline. But the tank is very handy and keeps a good constant pressure for you over long spraying periods... i can CC a PF with one of these and a 0.5mm nozzle on a brush.. comes up a treat.

The smaller constant blowers that are typical airbrush air transferers im not too keen on. Im using one at the moment cos i broke my 2.5hp compressor.
They condense inside much easier despite water trap and once water gets in your line any good work is impossible.. if its humid the problem is increased. They also have to run themselves more often and so heat up to hot quite quickly despite the cooling fins.

They are quiet though which is an advantage cos i can work at night while kids are asleep, but my preference is a compressor with holding tank. Yes they also condense and accumulate water, but with a large tank, the water sits on the bottom and the air is transferred from the top, so ive never had water in the line with one of these. You have to bleed this off after use though otherwise it will rust your tank from the inside out and youll get rust down the line eventually and a blocked airbrush is a real pain!

The compressor you have should work fine Wotto, you may need to buy a few reducers to get the output down to the size of the airbrush line though.

One other thing that is an absolute MUST as far as in concerned is a small air regulator that attaches to your brush.. you can control airflow at your finger tips this way and leave the compressor alone.

Airbrushing is really a balance between thickness and amount of paint flow, also how fast you propel it... this will give you shading effects and also allow a full "fill" of an area as well as thin lines etc.

Heres the airflow adjuster you will need..... these are essential!

http://cgi.ebay.com.au/AirBrush-MICRO-VALVE-Speed-Coupler-1-8x1-8-M-F-/160441017707?cmd=ViewItem&pt=AU_Toys_Hobbies_Model_Kits&hash=item255b07a56b