Can you make an external HDD bootable leopard and then make a windows partition?

No. Boot Camp only works with internal hard drives.

 

Let me clarify my answer.

Besides it not being possible to install Windows on an external drive using Boot Camp, you also can't do it on an internal drive that you later put in an external enclosure. A Mac will only boot Windows from an internal drive, period.

 

not exactly true. I have been helping clients with this issue as of late, where the SATA cable inside their MBP failed and they needed to use both sides of there drive (Bootcamp and osx) there are utilities that will allow windows 7 to be used from USB devices.

the catch is that it has to have been installed from inside the machine, then have the USB patch applied then put into a removable case.

I am researching a method of installing directly to the removable drive from VMware or another source so I don't have to disassemble my 2012 MBP to have a similar disk.

/HBP

 

Booting from a USB device is not a Windows 7 limitation, it's a limitation of Apple's firmware. Booting EFI supports USB devices as boot targets. But the CSM-BIOS mode used for booting Windows, does not support USB devices as boot targets.

I have heard some newer hardware, e.g. 2011 Mac mini and maybe others, support booting Windows 7 from SDXC media. I haven't tested this myself.