Go to http://www.doom9.org/codecs-103-1.htm

In my experience, wmv thru Vegas produces a somewhat blurred background reducing the appearance of noise - the stand alone encoder will preserve detail at the expense of noise. Realmedia/video will soften the backgound as well, but works better in some situations.

There's tons of tuts on DiVX -> see digital-digest.com & doom9.org. Generally, the quality of the compression depends on the quality of the source, using 2 pass versus one, using vbr, quality settings where applicable (usually just smoothing amount).

If you're trying to get *SMALL*, do it 320 x 240 from a 640 x 480 source & let the graphics card blow it up by sizing the player to 200% (this can be done automatically with winmedia and realmedia within the referring file, ie: .asx file for wmv & .ram file for real.) IF the larger source raises some eyebrows, Try It! With more source data to choose from, seems a bit nicer picture results when really squeezing.