I know similar questions have been asked but I didn't see it in my forum search on "reduce bitrate".

I tried to back up Monsters, Inc. last night using DVDx. I thought I set the bitrate (in output setting, Custom Chapters) to 2000 which came out to just under 700mb per volume for 2 volumes. But when it's done, it was over 900mb per volume. The bitrate was set to 2600 somehow. My question is 2 folds: speed and quality. I can reencode from the DVD again using the correct bitrate this time, but this will take several hours and wear the DVD drive. Or which software can I used to convert the existing MPEG2 files on the HD down to 2000 kb/s and hopefully quickly? Does reencoding a 2600kb/s MPEG2 down to 2000 result in worse quality than encoding DVD to 2000kb/s in the first place?
Thanks
Andy