A query...

It's PAL land here but I've just produced a couple of wedding dvd's that need copies to go to the US of A.

Are US dvd players capable of playing PAL dvd's?

If not, is it possible to convert PAL Vegas wedding projects into NTSC so that I can cut NTSC dvd's?

LATER...Opps. Looks like I should have looked at the Vegas help. I've just thought of doing that and found the conversion appears to be a pretty straightforward task.

Definitely do an NTSC version.
As you discovered, it's fairly easy to do.
While there are some DVD players in North America that will play PAL, my experience is that there's still not too many of them out there.