Running windows on a mac

Hey all,
I have run a quick search but not found exactly what I was looking for so I thought I would ask and see whether you guys can help me or not.
Basically, I wish to play Rome Total War, however I think the game is probably not important, with my friends on Windows, which isn’t possible cross-platform. However, I am aware it is possible to run windows on a mac? How exactly is this done?
Naturally, as I wont be playing this continually, I don’t wish to suck RAM from my mac when I’m not using my windows partition. Is there a way to just install windows separately, being able to use that without OSX running and vice versa without affecting future performance of OSX?
Cheers,
Ed
Answer #1
Oracle Virutual Box i think, but google a bit about it to know more
Answer #2
BootCamp for Intel-Based Mac
http://support.apple.com/kb/HT1461
Answer #3
BootCamp. Using Goole is easier: http://www.google.com/search?client=ubuntu&channel=fs&q=how+to+install+windows+on+mac&ie=utf-8&oe=utf-8
Answer #4
Use VMware to run another os on a mac, but since its just for a game use bootcamp.