Ubuntu or Windows for my desktop?

So I've been kicking around the idea of getting a desktop computer with a big monitor recently. I just feel like I could be more productive in that environment. What I want to know is should I stick with Windows (which I've always used) or switch to Ubuntu? I've played with Ubuntu before but am worried that it may have some shortcomings that I'm not aware of. Please help me out and sell me on either Windows or Ubuntu.

For the record I plan to do some web dev work on this machine (I'm a student).