So after spending too many hours trying to get selenium to work in Windows Vista/Windows 7, it turns out that you must run the selenium server from an administrative command shell.
The easiest way to do this is to search for “cmd” in the start menu and then right click on the “Command Prompt” item that comes up and select “Run as Administrator”. After you have the shell open cd to the correct directory and run “java -jar selenium-server.jar”. You can then run your selenium tests from a normally privileged shell.