I've just upgraded my macbook to snow leopard from tiger, and after opening an application I have to use yearly for work, I discovered that the program cannot function in Snow Leopard without a $275 update which my job will not pay for. Before I decide to either spring for the update or downgrade back to Tiger, is there a way I could use a hard drive partition to run two different versions of OSX? My concern is if I downgrade on any section of my hard drive it would downgrade the entire thing. Is there a way of doing this? Any help would be greatly appreciated, thank you!!!