well, what's your budget? And what are you going to do with it? If your a casual user, and just want something to play your mp3s and video (like Apple Trailers and flash cartoons and what not) and want to spend very little, you can get a
SoundBlaster Live for like, $30. It's nothing fancy though.
If you want a bit more, the
Audigy 2 is around $100 (the higher end Audigy 2 can get like, 2-3 times that), and is probably what I'd buy, since I think it's a nice balance between quality and price, imo.
I think Creative will also give you deals on card/speaker bundles, if you need that (a good sound card is worthless if you have bad speakers). You mentioned cost effective, so I won't go into the really high end cards.
To be honest, I haven't ever had much to do with sound cards for the computer. I've bought a few, and I've never gone wrong with a Creative manufactured card though. They've not failed and I've not noticed any performance issues - and they definitely give better sound than standard on-board sound. Some of the other techies on the board might contradict me or have more to say on this. If so, I'll bow to their greater experience.
