Just today I replaced my old mouse (which was fine for general use) with a Logitech MX518.
I have pretty big hands as well, but I actually went in to best buy and played with the demo a bit, and it felt pretty nice (and filled my hand better) than the old one.
I've heard good things about the Razer Lachesis & Diamondback (diamondback is in the same price range) mice, and not-so-good things about the MS sidewinder gaming mice - but while I'm okay paying $50 US for a mouse, $80 US seems a bit much.
I have a microsoft habu for sale.... basically a microsoft body with razer internals. its pretty new as well, let me know if your interested

i use the Habu. it's a co-effort between Microsoft and Razor.
it's a little over a year old, no problems yet.
dpi switching, programmable buttons, blue lighting.
it's a decent mouse worth a glance. I haven't used any of the logitech mice so can't offer a comparison, sorry.
I have large hands (I have to buy XL or XXL work gloves) and I use a Microsoft Sidewinder. Great mouse and very comfortable for big hands. I actually chose it because of the way it felt in my hand... great size then I added as much weight as it would allow (30grams) and it has been an excellent mouse!
