FAT32 versus NTFS?

I have 1TB ext drive (partitioned into two drives) that I have been using with my MAC OS 10.5.8 for a few years now, it's hardly ever been used as it was my second back up. I analysed in using Puran and it's pretty tidy. I now want to start using it as a back up hard drive with Win 7 and since I originally formatted it on my MAC as FAT32 it seems to work fine.

My question is, would I be better reformatting it to NTFS now I am using it with Windows 7, or just leave it as it is? Apart from the obvious where I can use it with both platforms what are the advantages and disadvantages?

My main concern is reliability. If it has been pretty much hardly used since I filled it with data would it be better to reformat and resave everything again, or could I just run some disk check on it to test for corrupt data?

Well I decided just to keep it as Fat32, seems to work fine if a bit slow. It's handy for moving files between my sony and my old mac. I don't want to set up wireless file transfer, tried it before with Vista and it was a nightmare. I'm sure ti works better now, but still I don't want my Mac OS coming anywhere near my lovely windows 7.

I'd quite like to get my HD copy of 2001 on my vaio, but my usb clip is only 4GB as well.