Parallels5 always defaulting to bootcamp

Hi,
New to Apple and Parralells so please help.

I have two Virtual machines
1. Windows 7
2. Boot Camp Win XP

Running latest Mac Snow Leopard when I double click on a word or excel document in tries to open bootcamp every time. It then reports an error becuase screen memory is too low and warning that it is running within a virtual machine (which I can understand). I want this to run the Win 7 VM as default and never select Boot Camp. Ive tried moving win 7 to the top of the VM list but same result.

Can anyone help?

Many thanks,

Mike