Photoshop makes my sad :'(

There is no more space I can possibly free up on my C partition, and I really need to get Photoshop installed (just reformatted). Does anyone know a way to trick Adobe CS installed without having the 1.5 gigs it requires on your startup disk? Or is there a way to allocate space from my other drives onto my C drive?

Attatched is an image of the error I have been getting…