converting to xvid for internet

[KayAt]

I need to convert some .avi files to xvid or divx to post on the internet at YouTube

They suggest 320/240 and mp3 audio and I thought xvid or divx would give me the best
quality. I could maybe use mpg files as each is less than five minutes and would probably stay under the 100MB limit but I wanted to get the best quality possible.

Could someone give me advice on which format would give me the best quality on
YouTube?

I am also considering making my own .flv files and embedding them, would that create
better quality? I don't want to invest the money if the difference is minimal.

Thanks

[Baldrick]

Easiest: AutoGK, select Xvid and MP3, set the output file size to 100MB and convert.

Best: I don't know...