I think I've accidentally changed the file system on a Mac configured Lacie external 500Gb firewire drive when I plugged it into my PC (okay, it was a dumb idea). When I plugged the laCie back into my MacBookPro, it won't mount (System file now reads Ms-Dos/Pc, I believe it used to be Mac Extended.
Any way of chaging the file system without destroying the data?
MacBookPro 2.33 Ghz Intel Core 2 Duo
LaCie d2 500 Gb big disk (triple interface)