best codec for rendering AVI files in Sony Vegas

i have for footage in 16:9 30p

i am applying some effects and color correction using FXBlue

after i rendering with default ('Best') AVI DV widescreen in sony vegas .. my video quality dosent look that sharp, it look more like i am playing a video cassette... what codec should i use to reneder AVI in Sony Vegas for the best possible quality ?

also i need a 20 minutes video not to go over 4-5 GB

i've had good results with the cineform codec.

I have just recently come across the Lagarith Lossless Codec

http://lags.leetcode.net/codec.html

and have achieved some very nice renderings from Vegas with it. In fact it is the best I've found after spending several hours doing systematic comparisons of various codecs (done because I have some footage with some very fine details which need to be preserved).

Lagarith not only looked better to me than some other really good codecs (like Huffyuv and DivX) but creates reasonably small files -- in my trials, they were 10-20% the size of the underlying, uncompressed files.

Hope this helps... good luck