Hard drive question internal?

I have two hard drives. One is 500 gb and the other is 320 gb. My 500 gb is almost full and I was thinking of using it for storage and using my 320 one which is empty to install an upgraded bit of windows 7 on to make it runner better. Is there a way I can connect my 500 gb to my computer in a way that makes it almost like a flash drive? I'd still like to access my files from it while still using my new hard drive and with out having to discontent and reconnect them each time from my computer.