QUOTE
Can I connect the speakers to the standard output? The mini stereo jack?
Probably... the speaker system decoder (assuming you are buying a package and not just the actual speakers) may have a stereo input.
QUOTE
If I can will I get 5.1 surround?
No, of course not. 2 channels cannot deliver 5.1 channels. Your decoder box might have a ProLogic or similar decoder to translate 2 channel signals to 5.1 channels, but your PC will not be able to specify which sound go to what speakers (so dolby digital, dts, and 5.1 channel video games will not work as intended).