Ok, so is it only for music or will it be used for HT duties as well?
If its only music, is there any reason you might be averse to headphones? For the price you can get headphones that will be much better for music. Just something to consider.
So what is your budget exactly? You say a couple of hundred, but I don't know if you're including everything in it or just the speakers.
Since music is your aim, if your motherboard has digital out then I would say use that. Audio drivers in general in Vista are terrible across the board so I don't think a sound card will alleviate the problems there. Its not as bad as that sounds as it should be pretty easy to get good 2 channel audio out.
As for the speakers themselves,
these are pretty popular and not very expensive (and if you're feeling up to it there is some moddifications you can make to improve the sound for little money). They don't look half bad either, just remember they are big, probably as big as the complete Promedia 2.1 set including the subwoofer. There's a few other brands that have some bookshelves around that price that aren't bad at all for the money. For the lowend you can pick up something
like this (they also have a 10" and 12" for a little more each).
If your hard budget is $200 total then I would say grab one of those cheap bookshelf pairs, a Sonic T-Amp (about $30 I think), and something that can feed them a pretty good signal (so a sound card or possibly a DAC). Or possibly use your motherboard for the time being (really shouldn't be too bad, modern mobos are actually ok) and save up for a reciever and sub or possibly better bookshelves.
Some other options:
The Klipsch i-Fi is good, but they've been discontinued by Klipsch and so can be hard to find. I know Best Buy was running them on clearance for a nice price for a while but they're probably out of them now.
These I think I heard pretty good things about. They should be good for music. The sub can be a bit of a problem although I think they might have a set that does include a sub. I don't recall off the top of my head.
There's probably quite a few other options, and there's several other people on here who will be able to add to it.
The last thing is just some extra info that would help people in recommending something:
Music only? What kind of music?
Hard line budget and what is included in that (everything, just the speakers).
Are headphones a possible option?
Are there any space constraints (so no reciever and large bookshelf speakers and sub)?
Is a sub a necessity (by answering the others you will probably answer this)?
Don't forget the software (by this I'm talking about what you use to listen as well as what format you have your audio in).