sound card is not needed imo, also the 780 mobo is a bit more but has more upgrades (not to mention tri sli heh).. I would downgrade to a smaller power supply (unless you plan on having more then one vid card)..
Here is my new rig I purchased for under 900$ (includes vista, does not include video card because I already have a decent one)
If you don't need an OS, that saves some decent money ;P
http://www.newegg.com/Product/Produc...82E16811119137 - Case
http://www.newegg.com/Product/Produc...82E16813188024 - mobo
http://www.newegg.com/Product/Produc...82E16819115036 -processor
http://www.newegg.com/Product/Produc...82E16822136161 - hard drive
http://www.newegg.com/Product/Produc...82E16817371015 - Power
http://www.newegg.com/Product/Produc...82E16827135168 - dvd burner
http://www.newegg.com/Product/Produc...82E16820178163 - RAM (only purchased 2gigs, I have 2 extra gigs I am putting into it)
http://www.newegg.com/Product/Produc...82E16832116488 - (OEM vista, one time install.. CHEAP)
total for me:
Subtotal $821.92
Tax $0.00
UPS Ground $29.16
Rush Processing $2.99
Order Total $854.07