How do I install Bootcamp on my system.

Grateful for your advice please.

I have a MBP running Lion. My hard disk is partition into two parts, with the secondary partition having a Snow Leopard system.

I now wish to run Windows with Bootcamp.

When I run Bootcamp Assistant - is says I should install the latest drivers from Apple.

When I try to do this I get a message saying they can't be installed because the
drive should only be formatted in one partition.

Is there a way around this?

Many thanks