Man first off, try the onboard sound. My onboard sound has hd outputs. If you do go buy a soundcard, get it from someone else besides creative. We are talking the company that would not write vista drivers for a lot of their older cards to force people into upgrades. So if a few years down the line you want that problem, that's your call. But honestly, take your 30 bucks, buy a good set of headphones or speaker, I'm betting you will be happier.
Even my Gigabyte board which is an sli AM2 board for only about 100 bucks has 7.1 hd sound output. I seriously would try the onboard first and see how you like it before dropping 30 bucks on that soundcard.
A lot of guys will probably tell you it's not that much. If you are an audiophile and really listen, you may hear some difference. For me, not a big deal. But I use my rig for games and what not. But I still would buy something other than creative if you buy a card. I know there are stories floating around that creative actually would not make vista drivers for some older cards and just stopped supporting them. Or that for some of the older higher end cards, they even released crippled drivers and the cards could not perform as they had before simply because you upgraded the OS.
If I'm right, one guy even hacked their drivers and was rewriting them so they would work better with Vista, and then creative threatened to sue if memory serves. So myself, I might buy an mp3 player from them, but not a soundcard at this point. That's just me though.
I have the $30 card on a Vista machine. Windows found the right driver by itself. No worries anymore. The self imposed boycott of creative must have circled the globe because they came to their senses in a heck of a hurry.