1:
Windows XP doesn't support burning to DVD-R discs via Windows Explorer as far as I'm aware.
2:
You need to use Nero Vision to convert the avi to MPEG-2 (or is it MPEG-4?) video used by DVD video discs. However, most modern DVD Drives can also read Divx encoded avi files - either in the root of the DVD, or organised into folders - I used to (naughtily) download episodes of CSI [LV/NY/Miami] (the UK is about a whole series behind usually) for my mum, put em straight onto a DVD-RW in XVid (it's like Divx, but better
) and she could watch them on the TV.
Anway, I'm digressing. Bold parts are important.