with $400 dollar budget i wouldn't worry about sound card, here is my recomendation. That AMD will be holding you back
new board.
Abit P35p for 75 after rebate
http://www.newegg.com/Product/Produc...82E16813127049
new card
ECS 8800GTS for 169 after rebate
http://www.newegg.com/Product/Produc...82E16814134037
new cpu
Intel E6550 for 159
http://www.newegg.com/Product/Produc...82E16819115030
after rebate = $403
oh right, you will need new DDR2 memory as well, add about 40-50 for 2GB DDR2, or about 60-80 for 4GB DDR2