No Minidisplayport machine can run 10.3 or earlier. Go to Apple menu -> About This Mac to tell us your operating system, so someone can move the thread to someplace where you can get a better answer.
Also VGA is not a good standard to watch from mini-Displayport. You are far better off with DVI or HDMI. HDMI at least if your Mac is new enough, you can get audio. See this knowledgebase article:
http://support.apple.com/kb/HT4241
Once you determine the age of your Mac:
https://discussions.apple.com/docs/DOC-6413
and if it is too old, see these solutions to get your Mac to transmit both audio and video to the TV:
https://discussions.apple.com/docs/DOC-2821