Yeah, allmusic.com is one of the best resources on the net, if not THE best. Try allmovie and allgame.com too. allgame isn't that great, but allmovie is really good. I've used allmusic for years, and even used it in a school report :) They've got books in print but for some reason they list free, updated information on the internet. Who knows...

Anyway, I've got an interesting link about bitrates. It's mostly a review/comparison of about 4 encoders, but there's alot about different bitrates.
http://arstechnica.com/wankerdesk/1q00/mp3/mp3-1.html

I don't know who said that even audiophiles could not tell the difference between 128 and wav. I'm no audiophile but if I listen to a file encoded at 128 and an original CD. There's no question. I even did one of my CDs at 320 once just to check, and the difference is unmistakeable. I haven't done alot of testing at only slightly higher bitrates, but I imagine it could make some difference.

By the way, what do you mean your Variable Bitrate is set at 6%? All my AudioCatalyst has is 5 settings from low to high. what exactly is the VBR?