Re: /boot as FAT32?
Drive letters are Windows only; they are completly irrevealant to Linux. You could format your one partition as FAT and mount /boot to it, but there is no reason to do so, and would only greatly weaken your Linux system.
What you should do is simply install one of the Linux bootloaders; either LILO or GRUB. They are installed to the MBR or to one of the partition superblocks, and can boot both systems. The filesystem which it is formatted as does not matter.
AMD Athlon 64 3000+ | 2 GB RAM | NVIDIA Geforce 5500FX | nForce3 motherboard
Slackware Linux 10.2