How can I tell if my Linux install is in its own partition?

I have a Gateway netbook with Windows 7 starter. I installed the Ubuntu 10 version of Linux. But I don’t think it installed on it’s its own partition, because it never asked me about the size or anything of a partition or which partition to use. So, I followed some instructions on the internet to put Linux on its own partition, but how do I know its really on there?