Backing up OS X Leopard and Windows XP to same external hard drive ?

I am looking to get the new Apple ultraportable when it comes out [whenever that is]. Anyway, I want to run Windows XP thru Boot Camp to run some business applications. However, I have only one external HD that I use for back ups. My question is, will I be able to use this drive for backing up each individual OS? I know the the Windows XP partition and the OS X Leopard partition will be different formats [NTFS or FAT32 and whatever Apple uses]. Will I have to partition my external hard drive in the same way and back up Windows to the similarly formatted partition on the external drive and the same for OS X??? I am confused...and maybe I am over-complicating this.

Thank you for the suggestion but I still need an answer to my questions. Thanks 🙂

Posted this in OS X section...maybe that is a better section for this question?

Anyone?