I was pretty surprised to see that I have a version 4 too as I was almost certain it was version 5 but when I opened up the expansion bay... I didn't see the screws that the version 5 supposedly had. This is the link I followed to determine my version number
http://www.modchips4sale.com/which_chips.htm
They don't show a pic of version 4's so I don't know for sure but I'm pretty certain the screws aren't there. I think NightCrawler also said that if you only see two screws it's version 4 and more for version 5.
Anyway.. I wasn't aware that Magic 2 has a problem with version 4 R... is Blue Messiah a better alternative? Thanks in advance.