It might be easiest to find a dvd player that can handle both NTSC and PAL video and hack it to be region free. You can find a list of such players over at videohelp.com Who knows, your current dvd player may be one that can do this. Finding a player with those capabilities would be the best solution if you are doing this quite often. For just one dvd, you may not want to invest in another player.
It is easy enough to get rid of the region coding…you just rip to the hard drive with DVDFab HD Decrypter and it should be gone. http://www.dvdfab.com/free.htm
Converting PAL to NTSC is not so simple. ConvertXtoDVD claims to be able to do this, but the trial will leave a watermark in your video. Here are the instructions on how to do this with ConvertXtoDVD.
The only free software that I know of that might be able to do this type of conversion is FAVC, but I haven’t seen a guide for this specific type of conversion using this program. http://favcfavc.googlepages.com/
I would use the HC encoder if you try to do this, rather than Quenc. Both come with the program. You’ll need Net 2.0 and Avisynth to run FAVC, but there are links to download both at the FAVC site.