PAL to NTSC

is there a way to convert a pal mpg file to a ntsc, I have a movie I burned as a dvd in toast, when I burned it, it said it changed to pal, which its done before with no problems, but this time, the dvd either wont play in a dvd player, or if it does play, it looks all weird. the odd thing is that it plays on my moms dvd player just fine, but wont even play correctly on my mac. any help is appreciated.
and yes, I know the frame rates and bitrates and audio is different.