I don't see why QuickTime 6.5.1 wont work for you. You can use QuickTime Updater included with QuickTime 6.3 to update to the latest version. If it doesn't work you could go back to version 6.3. You should read the System Requirements page for QuickTime 6.5.1 to see if it it will work on your Mac. To make things easier I copied what Apple said about the MPEG 2 Playback Component if you purchased it.

"Note to MPEG-2 Playback Component users:

If you purchased the MPEG-2 Playback Component from the Apple Store online or received it with Final Cut Pro 4 or DVD Studio Pro 2, you are eligible to receive the new version for free. Learn how you can obtain this free update." I hope this solves your problem.