Updating from XP PRO -- Which Linux OS ?

I have little knowledge of the various Linux OS's. I am very impressed with what I've heard of Linux. I've done some reading, asked around a bit, and am not satisfied I have enough knowledge to make a good choice. I've been using XP Pro for several years and am seriously considering a Linux Distribution instead of upgrading to Windows Seven. 
My question:  What would be a good Linux OS for a Windows XP Pro oriented person to start with?