Maxtor One touch 250g HUGE problem

im a graphic design major and basically have 3 diffrent hard drives i work from. one in my tower, a small 80gig i take to and from class, and a perminent 250 external that i never take from home. heres when the problem happend, i took it to school and used it on a mac (video editing), everything was fine and i got data to and from it just fine...but when i brought it home back to my pc tower.... "this drive needs to be reformated" i didnt do anything i just disconnected it, and now im at school. tryed it on a mac and it said that it can not acsess the data volumes on this drive. Im really really scared as my whole portfolio, and everything ive worked for years is on this, and NOT BACKED UP. please someone shine some light on this situation.

the drive is a maxtor onetouch, connected on firewire.
-tom

If the drive was formatted using a Macintosh-specific file system (HFS+ for current Macs), your PC won't be able to read it.