Eloise, I do all my computing on the Mac, so I can't speak from experience about Windows. However, Videora (free) is (or used to be) a pretty popular file converter for Windows. A couple of web sites that you might want to check: afterdawn.com and videohelp.com both contain download links and advice forums that you might find helpful.
Please don't get offended at the following, but I'm going to pretend that you're starting from scratch. So, you'll need either a DVD ripper or VLC installed. If you have a ripper, just rip the DVD contents to your hard drive. Then launch Handbrake. Once Handbrake is open, toggle the preset panel to open and select "ipad". Then select your source folder that contains the ripper TS folder. Handbrake will find every possible file within that folder that it can convert. It assumes the largest file is the one you want and it will be the one that shows up automatically. If you want only the movie (no subtitles, extras, commentary, etc.) you can tell it to start. Really easy.
If you don't have a ripper, but VLC is installed you select your actual DVD as the source and proceed as above.
As for Nero, I've used their Mac software (Titanium and Popcorn) to convert/burn non-VOB files to DVD but have no experience going in the other direction. And I'm fairly confident that their Win7 programs won't look/work like the Mac stuff. The good news is that they have trial versions on their web site so you can audition it. But they're expensive. Me, I'd try the free stuff first.
Good luck.