Need a DAC for home speakers

Hi Guys, first post!

Seems there are some knowledgeable people here so I will see what I can find for my situation. 

I am moving into a new condo and I will no longer have my computer in the living room where I listen to audio on my logitech z-5500's. Instead I am using a laptop computer with a single output for headphones, while the z-5500's require three outputs or a digital output for all of the speakers in 5.1 to function properly. The main computer now has a dedicated office.

I will probably need a usb DAC to make these speakers work decently from the laptop right? I understand that most usb DAC's are designed for headphones, but are there any designs for external speakers? Does it matter much? I am willing to spend ehh.. we'll say $600 or less for something to do the trick =P. I very well could get away with less I'm sure and get some creative labs ones or something, but honestly I doubt they will be sufficient for home audio from high bit-rate tracks. Most of my tracks are at 320 bitrate or better. 

What do you guys recommend in my situation? I am keeping my z-5500's to set up in the living room in surround, so what will work best? Thanks!

Thanks for the suggestions guys! Seems like the Behringer uca202 will probably do the trick as stated, but I probably should have mentioned that I was hoping to get a DAC (or something like that) which actually improves upon the soundcard my laptop currently has. Would this do that? I really don't mind spending in the $600 range to get something decent that could even hold up if I were to ever improve the speaker setup I'm currently using. The Z-5500's are great as computer speakers, but I know that they may not satisfy me forever in a living room arrangment. 

To add another factor into the mix, I also have a Sennheiser PC360 headset and could possibly use it for the headset when I'm not using the speakers. 

What do you think?

Okay, thanks. I will look into my options then. Eventually I'll be back to upgrade my speakers!