If the MPEG2 is compliant it would still multiplex to VOB but shouldn't need re-encoding.
Nero or other commercial programs like Ulead DVD Factory etc should do this for you but they tend to take all of the customisation out of the equation. If the MPEG2 files you have aren't DVD compliant and they need re-encoding, these kind of programs mightn't get the frame rate right for example, and you wouldn't be able to alter it -- so you'd end up with audio out of sync. A frustrating waste of a disc.
You could try burning a non-compliant DVD in nero though. In this case it should basically just accept your MPEG2 files and not fuck around with them. There's no guaruntee that all DVD players will play the disc, but as long as yours do you might not care. So you could do a test disc. Theres a setting when you create a new DVD Video from the wizard that you should be able to change to this effect.
Your best bet is probably another program if you're willing to look into the settings a little more. I'm not sure what the latest TMPGenc Plus is capable of, but it might be able to sort this out for you.
3gpp is great for movie file conversion, but I don't know of a way to get it to do VOB files or anything -- I've been using this for making videos that will play on my Sony Ericsson but its also useful in general for creating and converting movies. It uses the ffmpeg core, and it can be really fast. Once you've got a profile set up, you just drag files onto the program. It doesn't get sweeter than that.
