Can I play DRM music from iTunes on my Android? I thought that DRM content on iTunes could only be played on iTunes, but then I saw SongBird, a non-Apple application that can play DRM protected music.

Is there an app for that uses similar technology that can play my old iTunes purchases?

Is there any other ways I can play my music on my Android (Wildfire)?
This has basically been answered in the comments above but I'll wrap it all up into an answer:

No, you can't play songs that have Apple's Fairplay DRM protection on your Android phone without removing the DRM protection (which technically violates Apple's toc).  As Edarerathis pointed out, Songbird doesn't actually support Fairplay DRM'd media, Quicktime does, so SongBird (like RealPlayer) uses Quicktime to decode the songs and play them.  It wont work without Quicktime installed and so you can't use this functionality in Linux or Android.