Roger
Many dvd players play both PAL and NTSC. In fact, I send NTSC dvd's to a buddy over the pond and he plays them just fine. If you want to know, I'd probably use MediaInfo and drop the whole DVD folder in it. For one in the video section you would see
Video
ID : 0xE0
Format : MPEG Video
Format version : Version 2
Bit rate mode : Variable
Width : 720 pixels
Height : 480 pixels
Display aspect ratio : 16/9
Frame rate : 29.970 fps
Standard : NTSC
and for the other:
Video
ID : 0xE0
Format : MPEG Video
Format version : Version 2
Bit rate mode : Variable
Width : 720 pixels
Height : 576 pixels
Display aspect ratio : 16/9
Frame rate : 25.000 fps
Standard : PAL
You will also have less quality loss if you leave it in native format, NTSC or PAL.
Jeff