My streaming calculator (no longer available for download than I can find) says about 200MB per hour of 512Kb/s wmv. Presumably 400MB for 1024Kb/s. If you’re concerned with space and the number of CDs/DVDs you’ll need for 11 hours I suggest that you’ll find your sweet spot somewhere between these two bitrates.
You should see how 512 works at 320×240 with your content, and try viewing it at 640×480 and fullscreen – probably a little fuzzy, but may be acceptable for conference video. 1024 at 640×480 should look very good at native resolution and full screen if the source video is good.
Let me grab that slide rule :-0 you could probably get all 11 hours on a single layer DVD-Data at 1024Kb/s. (but you might want to test a little first because its a tight fit and 11 hours of video is a lot of rendering!)
If nothing but outstanding video will do, you’ll probably find it somewhere between 1400 and 2400Kb/s bitrates with wmv. But I use 1024 frequently.