Buying office software requires matching your computer's capability or engine, determined by the type and speed of its processor, and resident horsepower, or the amount of random-access memory (RAM) combined with hard-drive space storage.
In a game update that was released in July 2005 for Halo 2, the developers have included software that scans for "modded" Halo content on the Xbox hard-drive.
A detachable 20 gig hard-drive is upgradeable and it can handle memory units starting at 64 MB.
Similar conditions apply for portable movie players, be them DVD or hard-drive based.
Make sure you have enough space on your hard-drive for your downloads.