Nowadays, you practically don't need expansion cards. Sound cards are reserved for professionals, rich people, and audiophiles; all of which have really expensive/good equipment that can actually transmit the difference (except for the last group, they may have it for no reason). Motherboards come with so many ports and features these days. You don't need to add USB. FireWire is useless. They still make boards with VGA for some reason. The only expansion card that you might need is a wireless card, but even some motherboards come with built-in Wi-Fi these days.
Essentially, if you have average speakers or are just planning to play songs through your $50 Sony headphones, it won't matter. Onboard audio is more than enough for you...