Soundcard Vs. Audio Interface, What's needed to connect G4 + Monitors ? Options

[Fields]

(maybe I put the original topic in the wrong section)

Hi Everyone, always enjoyed the info you all share... I dug around the old posts, couldn't find anything related to my question...

I have a PowerBook G4 (400mhz, 10gig, 640mb, original soundcard). I write all my music in Reason, and I'd like to get some decent powered monitors.

Common sense tells me not to just take the headphone 1/8'' output, throw a 1/8''<to>1/4'' adapter on the cord and plug it into the 1/4'' input of the monitors.

So my question is... Do I need an external soundcard? or just an audio interface? (like that handy 410)

I'd like to be able to connect my pc to the setup as well, so I can mixdown my Reason tracks in CubaseSX2 until I get the G5.

Thanks y'all.
-Fields
http://www.zebox.com/exillon
http://www.zodrecords.com