Just a small addendum to Glenn's excellent tutorial. Doing some research into all the issues with levels one thing I came to realise is digital still cameras and scanners work in Computer RGB. Although this can be adjusted to Studio RGB within Vegas it can get a bit messy. The other approach is to adjust in PS using the Levels tool by setting the output range to 15 to 235.
The other place I just realised I'd fallen into this trap was using stills from my DSC for DVD menu backgrounds, one in particular has a lot of detail in the blacks, some of which was getting lost when the player clipped the blacks to legal.
Bob.