Can I dual boot Win7 and Snow Leopard with Win7 already installed?

Ok I was wondering because i really want to dual boot and stuff, but most of the guides im reading it says i have to install OS X first. The thing is that my Laptop already came with Win7 and no installation disk so can i still dual boot, Like using chameleon on the OS X? i would appreciate the help. Oh i am running a AMD machine and some of the guides i read said that i can do this on my machine even were i downloaded the ISO said Intel and AMD SSE2, SSE3 so my computer has that just wondering if i can with no win7 install disk by just partitioning my hard drive i would like this info asap but thank you in Advance :)