as everyone has already said region and format are separate constraints put on your player and disc. if the two don't match you're likely to have problems.
a region free disc only solves half the problem...it will play in a palyer regardless of region. you still have not solved the problem of format. Most NTSC players over here in the US actually will NOT play PAL discs regardless of region. You'd have to buy a multi-FORMAT player.
as I've discovered on this board, many PAL players DO play NTSC discs across the pond and there's no need to buy extra hardware.
you'll have to check to see if your player supports both formats.