Quicktime is integrated into the Mac OS ... it is a part of iTunes, iPhoto, iMovie etc ... in your Applications folder you will find Quicktime Player which I think also is integrated with Quick Look (where you highlight a supported media file and then hit the Space Bar to preview it without actually needing to launch any app.
If you dig a little deeper and go into the Utilities Folder which is to be found in the Applications Folder, you will find QuickTime Player 7, which has a few more tricks up it's sleeve than the new QuickTime.
To go straight to your Applications Folder, in Finder you can use the Keyboard Shortcut"
Shift + Command + A
Or to go straight to the Utilities Folder, use:
Shift + Command + U