Do you have progressive scan? If not then you'll need to rip the discs and re-encode them.
What's he meant to do if he does have progressive scan?
I'd recommend using AVISynth with the mpeg2dec plugin (this allows you to use a .mpeg/.mpg/.m2v file as source for an AVISynth project). Then you can resize and crop in the same script. If you're lucky, your MPEG encoder will accept the AVISynth as input (TMPGenc Express does, for example), so you only reencode once.
I don't know about sharpening with DVDrebuilder, but you can sharpen with an AVISynth script. It's a very handy tool.
DE