PPC applications used the old "Classic" or "Rosetta" modes. That would put their age at about 6-7 years old. You just need to check and make sure theyre "Intel" mac friendly first. And since you're new to Macs, another thing: any file ending with .exe is a Windowz file and will not open on a Mac.
Here's some good reading for you. I hope it will help in your transition: