External harddrive question

Okay, so I bought a harddrive last night, its a western digital passport drive basically this and I'm having issues with connecting it to my 360 to watch divx movies off of and what not. I've read it may be a formatting issue and it should be in FAT32 formatting, and being that I'm a Mac user I put it into MS - DOS system file with my disk utility, which from what I've read is putting it into FAT32. But the thing wont be recognized by my 360 at all. I'm thinking that because its completely USB powered may be an issue too, but my iPod works, and that thing is essentially a harddrive itself. Any idea whats wrong, anyone?

get a good software like Partition Magic. Re-format the Hard Drive (to Fat 32 of course) it should work (it did on mine)

Yes, the issue is that the harddrive must be still partioned under NTFS. the 360 will only pick up FAT32 partions. I had the same problem with my external HDD. It has nothing todo with being 'Totally USB'.

Like the member above me posted, use partion magic as I think it's free software.