wow... guess I'm about the only nice guy in this forum.
ok, you go to this site:
http://trem.tjw.org/backport/ . Then you select your operating system (win32=windows). Rename your old tremulous.exe (in your tremulous folder) to trembak.exe. Then you download the NEW tremulous.exe, put it in your trem folder, and start up trem. Then you press the tilde key (as stated earlier). This opens up the console. Then you type in the following:
cl_allowdownload 1
cl_wwwdownload 1 (these two allow server downloads, so you don't have to manually download each map)
cl_guid (your GUID is your unique number, this command shows it).
cl_guidserveruniq (1? I'm not sure about that.) (this one makes your GUID unique to every server, if you want to become admin)
Now, join a server. If you want to register to that server, open up the console and do the !register command (note that not every server has one).
When you quit, you might notice your folders have changed. Now, the path where autodownloaded stuff gets safed is at C:\Documents and Settings\<username>\Local Settings\Application Data\Tremulous. Don't worry though, you can still save things like HUDs and stuff in your regular base folder. It's just the autodownload stuff that goes to this path.