This is the only option that i can think of, and it probably won't work. If you have a few days to burn, you can try it. In general I would say this isn't possible, especially because of the fact that you are running two different bits ;)
Make 3 partitions
- Win 7 32
- Win 7 64
Install the OS's as normal, and then install all applications on partition #3, into the same directories, and see if anything breaks. Maybe you will get lucky, but I doubt it.
Options for the VM (VM is 32bit, host is 64 bit)
- Do dev on the host machine, but debug in the 32bit using VS remote debugging, if possible for what you are writing. If it's drivers, i'm guessing you'll just be staring at minidumps
- Install VS in the VM, and then use vmware's 'app sharing' thing to make it look like you are working on the 64 bit site. Same goes for office.
Even better would be to invest $100 and buy a 500GB drive. I've bought more expensive things just to make my work life better, even though I dont' get reimbursed for them.