Well, SLI 480 beat the shit out of the 5970 when it comes to using high AA, even the 4GB 5970. If AA isn't the case, then the 5970 is nearly, or just as, good as SLI 480.
Onboard sound? I remember my old Asus mobo for my LGA775 had "HD 7.1 sound", yet it made horrible crackling sounds on my...
1) What will you be doing with this PC? Gaming? Photoshop? Web browsing? etc
Gaming as well as Photoshop/Lightroom
2) What's your budget? Are tax and shipping included?
22 000 NOK / 3 500 USD
3) Where do you live?
Norway
4) What exact parts do you need for that budget? CPU, RAM, case...