How to pack it:  whenever possible, try to get styrofoam shippers and check your wine as another piece of luggage.  On most flights from Argentina to the USA, the 2 piece per person rule applies, so if you have only one bag to check you should be fine with checking the wine shipper.  If you already have 2 suitcases, you may still get away with a styrofoam shipper depending on the total weight of you two regular bags.  Check with your airline for details.  If you must take your bottles inside your normal luggage, try to have them in bubble wrap and abundant tape, so as to try to keep the liquid inside in case of breakage.  This will be your only protection against having all your clothes & other belongings stained.

Upon arrival - declaring your wine to United States customs:  United States customs is very easy-going with wine, provided you are up-front and 100% honest about how many bottles you are bringing in.  Make sure to specify the exact number of bottles you are carrying, and write it down on your customs declaration form.  If you are carrying more than one case (12 bottles), you may get asked questions, but dont worry.  Just explain that the wine is for your personal use and is NOT for resale (this is all they worry about).