Yes you can but it can take a long long long long long time. I tried to do it a few times and it took forever. Your best bet is to buy a dvd player that will play both NTSC and PAL DVD's. There is one by a brand called diamond.
For ways to convert try these links:
http://www.google.ca/search?hl=en&q=%22ntsc+to+pal%22&meta=