Thanks to my friends detail explanations, now I'm more interested to run a Tor client and Tor relay all the time using the Vidalia Relay Bundle just to help other people out there. But my problem is, how can I run Firefox from the Tor Browser Bundle alongside with the Vidalia Relay Bundle? I don't want to kill my previous Vidalia process just to run another Vidalia process from the Tor Browser Bundle.
Since some releases of the Tor Browser Bundle 2.x the control ports for Tor relays and the Tor Browser Bundle are different. The socks port is different, too.
There should be no problems with running a Tor relay (or bridge) while using Tor Browser Bundle for browsing.
The 3.x series of Tor Browser Bundle has Vidalia replaced with Tor Launcher so there should be no problems there.