Iomega Ultramax 500GB Firewire Problems...?

I'm not sure if this is a common thing but I've searched around for the past while and haven't found anything.

I got an Iomega Ultramax 500Gb external hard drive yesterday (from the Mac store in Glasgow). I tried pluggin it in via Firewire...but it didn't show up on the desktop or in Finder anywere. So i used the USB connection and it worked fine. But i'd rather use Firewire. It shows up fine in System Profiler > Firewire. It recognises the drive and everything in there. It just doesn't show up in Finder when connected via Firewire. Any suggestions?

Get the same problem on USB, Firewire 400 and 800, Can see the Iomega 1Tb drive in system profiler, but not in Finder. Bought from the Apple shop on Sunday. Only switched to mac three weeks ago everything going fine until I got this drive now it's just like having a PC and windows, cannot see the drive from finder but can still access the files on it from imovie as if the drive is mounted correctly. Must be a bug in finder. I thought I'd left this kind of rubbish behind when i ditched PC's but maybe not.

Kit - Imac 2.8 GHz Intel Core Due, 2GB 667 MHz DDR2 SDRAM ATI RadeonHD2600, MAC OS X 10.5.2 all software updates.