BrimstoneI've always just rendered to mp4 from vegas, what's the difference between letting vegas do it and exporting to avi then doing compression with handbrake?
Rendering to avi with Lagarith Lossless Codec gives you an uncompressed avi file, so there's absolutely no encoding or anything done to it to reduce filesize or streamline playback.* It's not completely necessary to do, but it makes sure that you have a "clean" video file you can then encode to your liking.
There's some advantages to it though. Say you render it to an mp4 file instead of an uncompressed filetype, then you realize after it's done that you're left with a file that's way too big to upload to youtube or wherever. You'd have to completely re-render the whole thing with lower settings to see if it's more manageable, as opposed to just running the pre-rendered avi through handbrake or whatever again with lower quality settings.
*(Actually it's wrong to say there's no compression/encoding done. The whole point is that all the original data is maintained/able to be reproduced when decoded, so the filesize is still pretty large, but probably not as large as if it was completely uncompressed)