8.0-RELEASE was done and configured with all the packages to be rock solid and no more changes for it (except security patches). I disagree that it's mostly for servers, it's for anyone who likes stability or is just starting an exploring of FreeBSD and willing to learn step by step.
8-STABLE is changing and moving ahead to 8.1-RELEASE then to 8.2 etc. This is quite obvious. Practically STABLE may have problems from time to time and some knowledge is required to overcome them.
To get 8-STABLE it's enough to boot any recent (could be even 6.4) CD and choose "Custom" installation. Go to "Options" and highlight there name of the release given, for example 7.2-RELEASE or 6.2-RELEASE as on figure 2.11 in
Handbook (please read). Then press Space and change what's written there to 8-STABLE. Review other options, choose media type - FTP because there is nothing for 8-STABLE on the boot CD. Then just proceed with sysinstall as described in the
Handbook
A few years ago I started with RELEASE and THANKS GOD. I don't know your level of experience but if you are a novice I would recommend 8.0-RELEASE: download DVD, get everything at once, read the
Handbook and ask questions here keeping in mind that it's not life time decision: you can later upgrade to STABLE if you want. But in meantime you will understand yourself do you really need STABLE or even CURRENT or you are quite happy with RELEASEs (and your hardware is perfectly supported by RELEASE).