Mac OS X supported both types of processor up until recently when all support for the old PPC processor was removed.
So moving from a PPC processor to an Intel processor, with a version of OS X that does not support the PPC processor, will result in some applications not running.
So, for under 40 bucks your Mac will have the current operating system. I just performed these upgrades on my mother's old i Mac and it worked great. I'm not sure if this is of any use but it says on the back of the RAM 2GB 1Rx8 PC3 - 10600S - 9 - 10- B1. I cannot figure out what kind of Mac you have, whether an i Mac, Mac Book, Mac Book Pro or what.
Apple suggests that a computer have at least 2 GB of RAM to run Mountain Lion, so you will want to perform that upgrade, as well. You can find installation instruction videos for a variety of Macs here: .
Although OS X is a very secure operating system, not patching the system means your computer is vulnerable to compromise from a less than well-intentioned individual.