It's not a real easy process. What you're actually doing is changing the frame rate from 25fps to 29.97fps. When doing this, most simple converters just double certain frames to make up the differences. This looks ok for slow moving scenes, but if the action gets going a little bit faster the screen can start to flicker.
Since it works on your laptop, you could try just taking the output of your laptop and plugging it into a DVD recorder. I don't think this will work though, because the frame rates won't be changed in this process and you'll get a rolling screen.
You could try
MPEG Streamclip which will rip DVD's to your computer's hard drive, but I'm not sure if it can convert from PAL(25fps) to NTSC(29.97fps) but it might work. If it doesn't I'm sure there is some PAL to NTSC software out there that is either free or very cheap that could convert the file that you rip.
All in all it can be a fair amount of work and often it's easier to just rebuy the DVD in North America. I know we have had to deal with this some at work, but I'm not sure what the final verdict was about our solution. I'll check in the office next time I'm in and let you know.