Where is my Minecraft world saved in Ubuntu?

I'm attempting to transfer my minecraft survival world to my new computer and I have a few questions regarding this. First, is it possible to transfer a world that is on two separate OS's (from linux ubuntu to windows 7). If so, I'm having trouble locating the file on ubuntu. And lastly, once I have (or rather if perhaps) the file on my windows OS where and how would I go about placing it so it would be playable?