File sizes converting WMV to AVI/M6 format

I am very close to purchasing the M6 mini-player but have a question on file sizes. Most of my videos are in WMV format. After converting a few small ones to AVI format, their size balloons as I expected. Will the AVI size be comparable to the converted file size for the M6? Just trying to figure out how much video I can store and what M6 to get. I see posts talking about storing multiple videos and am wondering how.
Thanks in advance,
Ken

to get acceptable video quality you should calculate 350 kbit/s for video plus 112 kbit for sound which results in 462 kbit/s or 200 MB/h. An average movie of 90 minutes in average quality should result in 300 MB. For best quality, add 30% to that value.

BobbyQ,
Thanks for the reply. That helped a lot and was what I needed. Order the mini player yesterday and can't wait to try it out.
Ken