Windows media grew from ASF files, and is now on version 9. There is a player available for MacOS, but I believe that Linux users are out in the cold here. There is a lot of resentment towards MS for a lot of things, but WMV is a perfectly good codec (unfortunately it has taken up to Windows Encoder 9 to give us two pass encoding, but it is here now). The encoder software is a bit harder to get round than Helix (which makes Real files) but once you get the hang of it it's not too bad...
Again, encode in WMV 8 for the largest user base:
Windows Media 8, one pass, 100kbps, 180KB
Windows Media 8, two pass, 100kbps, 164KB