Yes, I did switch the mouse buttons, it seems more natural to me. But whatever works for you....
I am going on 4 days or so since I started with the left hand, at first it was awful, really. But its gotten way better since then. It really changes the way you work, the right side of the keyboard isn't such a wasteland anymore. However, YMMV.
And yes, mouse selection can make or break this. Thankfully, I use the kensington expert mouse which works with either hand. This mouse works great out of the box with ubuntu btw.
I don't game with it though. I have a logitech G5 mouse for gaming and it is a right handed mouse, as you all probably know. But I must say I am not an everyday gamer, so its not such a big deal.
I never thought of trying it left handed( I mean really, it just doesn't seem right and you have to re-learn how to use a mouse) until I read an old thread on slashdot, seems alot of people have carpal tunnel and other repetitive stress with the right hand that was alleviated when they switched to left-handed mousing.