Mounting Fat32 on Leopard 10.5.5?

Alright, so I’ve been searching through apple’s kb and haven’t found a thing except references to 10.2. So basically here’s the deal. I have a 500GB WD external HD. It was originally hooked up to my linux server and I shared it out via samba. However, I am going to be doing a full backup of my macbook so I wanted to have the speed of a direct connection, so I attempted to plug it in directly. Problem is it won’t mount. Does Leopard have a 120GB restraint as has been noted throughout their kb? If so, why? Is there a way around it?