Midi can be used to record with, but not with a POD XT. The pod is outputting either analogue or digital (S/PDIF) audio. Any midi hookups are for things like automated patch changes.

What you need to do is hook up a line out from your Pod to the line in (not mic in) of your computer and then use whatever audio software you have to record with. You may have to get an adapter or two from radio-shack and these are normally 1/4" jacks to 1/8" jacks or 2x1/4" jacks going into a stereo (TRS) 1/8" jack.