I'd download VMWare Player, or VirtualBox, both of which are free, and then go to each of the distro's websites and grab their VM iso dowload and try it out. Nothing to lose doing it that way, as you'll soon see which you prefer. If they don't offer a VMX version for VMWare, you can simply use easyVMX to roll your own from their regular downloads.
Ubuntu is always a good starting place, as it is designed to be user-friendly towards new linux users. There are also flavors of Ubuntu with different GUI's, such as Kubuntu and Xubuntu. But remember, underneath all the fluff, most Linux flavors are all the same and so your skills will transfer.
What do you develop? If you're doing web development and just need a LAMP stack, most Linux distros are simple to get up and running. As a Linux novice, I'd have you go with Ubuntu again, solely because of the amount of documentation and tutorials out there for you to learn from.