Deffinetly choose between 2.1 and 5.1... 2.1 is easy as far as the speaker part goes, but alot of the good sound cars out now, have 5.1, which u could allways upgrade to later. And IMO, whatever u get for speakers, dont get bose.... Overpriced and dont sound good. Especially the pc ones.
its kind of hard to say what to get first though. i would most likley get a soundcard first, mostly because they are cheaper, then get speakers to match. But thats up to you.
I recomend some nice Klipsch or logitech speakers, both seam to sound good. For sound card, 5.1, 2.1, w/e, but deffinatly get 24 bit. I personally would go for the klipsch, because of the upgrade options, which, if you wanna spend another $100, you can get the preamp, which has pro-logoic 2, so you can make 2.1 into 5.1.... Anyway, go to a store and try out some stuff, see what you like. Hope i helped... Yay, first post.