Mac Upgrade

Can any regular mac version upgrade to Leopard or Snow Leopard?

I got a Mac about a year and a half ago and right now I have Mac OSx version 10.5.8 and I was wondering if I could upgrade to Snow Leopard, Leopard, or Tiger? Also, if so do you have to have the regular Leopard first to upgrade to Snow Leopard or can you just go directly and skip?

OS X 10.5 is Leopard. If you got your Mac new a year ad a half ago, it is probably an Intel based machine and you’ll be able to upgrade to OS X 10.6 (Snow Leopard) quite cheaply. Snow Leopard is supposed to have a significant speed advantage over Leopard.

mac pro graphic card upgrade (ati 5770)