Yea i have to agree with the above poster..some Mobo's come with some really good onboard audio, some dont. The gigabyte mobo that i have uses onboard 'realteck' audio and all i can say is that they sound pretty much the same as when i have my Audigy 4 in. So i took the soundcard out since its jsut a waste of power....
As for speakers i alwaso agree with the above poster, you will ALWAYS get what you pay for..the higher you go the better it gets, pretty much all the manufacturers are good, Creative, Klipsh, logitech altec lansing/.....all good, it just comes down to hthe buyer on what model to buy...From my experience i have to say that its better to buy a powerful 2.1 set rather than a weak 5.1 set...but thats totally up to you..
as for soundcards if you mobo does come with cr-a-p audio then i would suggets getting the Creative Sound Blaster X-Fi XtremeGamer
i have the audigy 4 and it isnt much different than then audigy 2zs.. the X-FI is newer and is supposed to soubd much better