I have to disagree with the other poster.
The motherboard audio is fine. It has 7.1 capability and fits most users needs perfectly. The age of bad motherboard audio seems to be past, unless of course you buy something really cheap.
I have both and have used both. Im also been a technician for many years so i get to play with all the toys and combinations that come out.
While Creative has been the choice for a long time generally and i loved them in the past, in the last year they have been complete crap quality not only hardware but drivers and software (a shame they have failed so heavily).
The creative x-fi has been horrible not just for me, but many other people. If in doubt go look at their support forums.
It has had a general hate for Vista especially and even though many games might say its made for use with Creative, it has caused a lot of not only wierd audio problems, but crashes as well even in XP.
Then also chalk up having to use 'Creative Alchemy' to even implement eax effects using Vista at all, which doesnt support everything btw, its just another reason not to use this card.
It just wastes a slot on the board if you ask me, especially if you use Vista.
They have had over a year to work with the drivers and have yet to make it decent. Its almost as if they just dont even care.
The reason for using cards in the old days were to have better audio, and to take processing power off the board.
Both of those reasons are pretty much bunk now concerning sound (again, unless you have a cheap ass motherboard, which were not talking about here).
Its gone into the 'box of cards' i do not use, and im back to useing on board audio on the motherboard as it presents no problems and works just fine.
sums up.
780i audio is fine.
creative is currently crap.