Are 2.0 desktop speakers or 2.1 with a subwoofer better for a PC?

It depends on the room and the content. A 2.1 system like the Klipsch ProMedia gives you noticeably more low-end for games and movies, but reviewers in specialist audio communities consistently note that small 2.0 monitors with proper drivers (Edifier MR3, PreSonus Eris 3.5) sound cleaner and more accurate for music. If you sit close and your desk has room for a sub on the floor, 2.1 wins for impact; if you want neutral sound and a tidier setup, 2.0 monitors are the pick.