The choice of an OS for a machine can be made by defining what you want the machine to do. I like Linux for it's wide range of possibilities and hardcore security. However, I am a diehard gamer and for that, Windows is the choice. What to do?
Well, I have a dual-boot rig. I have Windows XP Pro and Fedora Linux as well. The only time I go on Windows is for gaming, otherwise, I am on Linux and I love it. I do a lot of programming and graphics work, and with Linux, all the tools I need are already installed, and the best part is...I didn't pay for any of it.
As for 64 bit computing, there are only a small number of apps that are 64 bit, and an even smaller number that actually take advantage of 64 bit architecture. Try a dual boot rig setup. If you need help with doing it, let me know, I have a lot of experience with it and am happy to help.
I\'m already visualizing the duct tape over your mouth...