I think if you open up the ISO file with ISO Buster
you can tell. Someone correct me if this is wrong.
I think NTSC games will have a file that starts with
SLUS and a PAL game will have one that is SLES
other than that i would say you will have to read the DL
discriptions until you find one that says it is for the region
you want, i know most do not, and most are PAL, but i have seen
a lot of sites that list games like:
halflife_full_USA_Proper and so on.
Absolutely right, steimy, though sometimes NTSC-USA games are SCUS (for first-party Sony games). Also, Japanese games (SLPM, I believe) are NTSC format too.
The easiest way to tell, though, is to simply toss the disc into your PS2. If it flickers, then it is the opposite format of your TV.