Region code removal is a fairly trivial task and most DVD programs do this however PAL to NTSC conversion can be a much more complicated matter.
Rip the DVD to your computer and try playing it from there. PCs will play both PAL and NTSC content without any difficulties and that would let you know if that's what the problem is.
Effective software for doing this is expensive and it's a lot more difficult to achieve with freeware.
Kerry56 has a nice guide to AVStoDVD in the Video Edit Software forum here that includes PAL to NTSC that you might find useful, although I've heard that AVStoDVD is a bit hit or miss when doing PAL to NTSC conversions but you could still give it a try.
Alternatively, and this is the easiest solution, you could buy a DVD player that automatically converts PAL content to NTSC compatible format.