Most of my computing life i've gone for Microsoft mice, and I have never been let down. The hardware is solid, and has a lot of features (I like me some extra buttons!). As of 2 years ago I switched almost completely to Razer. I keep my Wireless 8000 bluetooth mouse around because it's a damn nice mouse and I like to keep peripheral wires to a minimum on my desktop (due to the way my desk is built). Plus if the battery dies in it (It lasts me about a week of heavy use) and I don't want to charge it, I can pop a AA into it and wait to charge it later, which is REALLY handy.
I have a Razer Lycosa keyboard on the desktop - I fucking love it. It has the "old style" laptop keys (I say old style because most laptops nowadays have that fucking horrible flat chicklet keyboard Apple popularized, and I fucking hate those uncomfortable things.) Plus it lights up blue, and has a mode where only "ASDF" are lit up (It IS a gaming keyboard afterall).
As for the mouse I use when I play games (specifically WoW) I have a Razer Naga, and I can't say enough about how sweet it is. It's lightweight, but feels absolutely solid. The cord is wrapped in cloth rather than being rubber so it doesn't catch or drag on anything. It has a 12 button number pad under the thumb that can be programmed to be used as a number pad, or you can set it up as anything you want using an Add-on for games like WoW. For general use it's great too, it's really comfortable and smooth for doing anything else, but it really shines when you use it for gaming. I usually have it set to the number pad, and for example, in Oblivion I have it set to change weapons and cast a few spells without having to move away from my movement keys.
Plus I have them set up for copy/paste, browser back and forward, home etc... I love using it for program/OS shortcuts where I can.
And Razer stuff comes highly recommended from me