Well, I'm a little late, but I'll kick in...
In my experience the size is about the same. WMV might have a slight edge in file size for comparable quality, but I'd say it probably isn't more than 5% to 10%. Without doing a lot of tweaking during the encoding process I find quality is about the same as well though I will reluctantly admit WMV is surprisingly good...sometimes it seems
a little better than plain old avi.
That said, I still use AVI (Divx/Xvid) for most of my DVD ripping purposes. The only place that I would hands down recommend WMV is if you want to play these files on a Pocket PC of some type.
Yes...I've gone over to the Dark Side.
I have both an Ipaq 2215 and an Axim x50v. While I can of course play Divx on them, it was a bit of a mangle to get it to work, but of course WMV worked right out of the box, and worked beautifully (in WMP).
But that recommendation would purely be for ease of use. When you are watching movies on a <4" screen at 320x240 or 640/480 the quality disparity is pretty moot (paticularly if render the movies down to around 250MB...using either codec).
But if quality is the big thing, I'd just say make sure whichever format you use, rip it directly from the source. I too have tried converting rips from one format to another (divx -> WMV...WMV -> divx...divx -> Mpeg1...etc...) , and while I've had surprisingly good results there is ALWAYS a loss of quality...even if you set the target bitrates, framerates and whatall as high or higher than the original.
But if you want to fool around with it, here's a couple of the apps I use.
- Aoa DVD Ripper
: Good feature set, and easy to use. Though it's been choking on the latest releases of the DIVX codec (maybe my setup is wonky, I'll know better after I build another PC from the ground up...). But Xvid works fine. Customer service is pretty good as well... http://www.aoamedia.com/dvd_ripper.htm
- Ashampoo Movie Shrink & Burn 2
: Very simple and effective for 1/1 conversions (ie Divx -> WMV). EXCELLENT for shrinking file sizes and lowering bitrates for play on portable devices (shrink by % or final target size). It would be nice if it ripped directly from the DVDs as well, but what it does it does well. Interesting company...you can make them an offer on their software and if they accept, that is the price you pay. This product lists for $50...I paid $16. Well worth it. Though it hasn't been updated since 2004, curious... http://www.ashampoo-root03.com/webcache/ht...uct_2_0137_.htm