airport express questions


The airport express is equipped with a mini-jack that is a combo: analog and digital toslink. Monster sells a variety pack of cables to go with the unit, including a mini-to-full toslink cable, and a mini-to-RCA cable.
How can I be sure that I am streaming digital audio with airtunes? Is there a box in some dialogue window that I need to check? For analog audio, which I don't want, does the airport express have a crappy internal DAC, or would the laptop be wirelessly streaming analog from its own crappy internal DAC? Laptop is a 5 year old Sony Vaio, windows XP. Thanks.
realremo
Just supporting/echoing your post, Rbsthno...sorry I didn't make that clear.
Realremo: Lifatec offers Toslink cables with the mini on one end and the full size on the other. I have used one from a Mac to the main system with good results (via iTunes). You can also get an adapter for almost pennies to go over the full size end and thus conform to your needs on the computer end.
Thanks Puerto, I have seen a link to their site in another thread, they are the ones who convinced me that maybe a plastic Toslink cable is OK. I am really interested in a mini/full toslink cable, just more of a pure thing than using the adapter, and will definitely check them out when I invest in PC audio.