Ok, I have exactly the same problem with me and my brother, only, I am not a programmer and I am not into writing lines and lines of yadda yadda in computer language.
I also run Windows XP (SP2) and my brother has a different account then I. In the program files/tremulous/base folder, there are not qkey files, however I can find on in the documents and settings/myself and my brother/local settings/application data/tremulous/base folders. Those that mean that Tremulous is reading different qkey files depending on the accounts?
Another question, can I create my own autoexec.cfg files in my documents and setting base folder and will Tremulous read it?