If all/most of what you play is TF2, then I absolutely suggest switching. I switched awhile ago and have been very happy. If you play other games, check Steam to see if those games are also on Linux, quite a few already, but a lot of the huge AAA titles aren't yet.
I switched a little less then a year ago and I've noticed an overall increase in FPS on Ubuntu/Linux Mint, and the huge amount of choice you have is amazing. For example, I used Ubuntus default interface, Unity for while, which is nice and very friendly to new users. If you like it, you'll never have to do a thing, but I wanted ot explore. Later I switched to Cinnamon, which is a much more Windows like desktop environment, before switching to GNOME Flashback for a more classic Linux interface I've grown in love with. How do you easily switch from so many totally different interfaces on the same OS(that I wanted to link pictures of but tftvs linking is broken)? One command: Apt-get
In Ubuntu (and in fact most mainstream distros), you NEVER have to use the "scary" Terminal (Command prompt as its called in Windows) if you don't want too, or don't want to do anything complex, so in general you never have to worry about it....but honestly...its easier and faster once you know what to do. Dropping in "sudo apt-get install cinnamon" and/or "sudo apt-get install gnome-flashback" get me a brand new desktop every time. You can install Steam, Skype, or whatever program you really want doing the same thing, just gotta google to find the proper command. Its quicker and easier then downloading the program and installing it manually, but thats what most people are used too.
ANYWAY, ranting. Linux is fun. Install it on a USB stick and boot from it and play from there first, just remember it'll be slower then having it actually installed. Be warned, the system is VASTLY different from Windows, so don't expect it to act like Windows, but don't think its bad because its different, I've come to think the opposite.
Oh, and don't be afraid to break things. When you first install, toy around, play with stuff, push and shove the OS to see what it can and cannot do. If you break it, just reformat, its MUCH easier to do then it is with Windows. Hell, you get to use the OS WHILE the disk formats, so go nuts!