probs viewing DVD's burnt on PC on my new powerbook? PLZ HELP

Hello,
I was told that macs were pretty much fully compatible with PC's these days.
I have some DVD"s that were burnt on my PC and for some reason they will not even register on my new powerbook's DVD player.
I did install software of an external PC/Mac DVD burner - and then inserted the DVD into the external DVD burner and it did finally register on my mac; but then I tried to copy the files onto the desktop of my mac and everytime, it would start transferring over successfully and then a short way through I would get some sort of transfer error and the copy would stop.

Thanks for any help.....
also is there going to be any problems for a PC reading any CD's or DVD's that I have created on my mac? Are there some settings or options or limits that I need to abide by? I need to make sure that any CD or DVD that I burn is universally readable by any modern CD or DVD reader.