the 3 addons and the 3 abyssea add on install data is included with the mandatory updates one must go thru if a client is out of date (meaning everyone who plays XI has the install data for those addons) having the registration codes from the PC ultimate abyssea collection will unlock those add ons and the abyssea ones on your 360.

Essentially the $20 was for the registration code which unlocks the content across all platforms since the registration code is tied to each account and not to each platform. Only the main expansion installs ( rise of the zilart Chains of promathia and Treasure of Aht urgan and Wings of the Goddess are tied to each specific platform which is a moot point cuz u have those 4 main expansions installed on your 360 and the PC Abyssea Ultimate collection also contains those installs for your PC.

In summation: since your friend bought you the $20 ultimate collection you are now fully equipped to access all the content released thus far on either PC or 360 as soon as you input the registration code that came with your Ultimate Abyssea collection purchase