I use Cool Edit Professional with an Ogg Vorbis filter, to encode my Ogg Vorbis files, and always use a variable bitrate. Using a constant bitrate doesn't really do much in terms of sound quality...it just creates bigger files.
Using Ogg Vorbis in constant bitrate mode incurs a hefty speed penalty (encoding is several
times slower than normal) and doesn't improve quality at all. If in doubt, don't use it.
VORBIS.COM is really the best source for info and utilities about the format.
Apart from a facelift, vorbis.com hasn't been updated in 3-4 years. Their list of software should definitely not be taken as exhaustive.
As far as encoders go, I like OggdropXPd. Just drag wave files to the fish icon and it encodes... Couldn't be easier to use. It can also tag, decode, and is highly configurable.
You can find the latest version here: http://www.rarewares.org/ogg.html
There are several different versions, just go with the one at the top. Choose the version that matches your machine's CPU or go with "generic" if in doubt (the only difference will be in speed, and probably not that big).