shovel - don't bother with full sus unless you want to spend a fair bit, cheap full sus is utter ***** and to be avoided.
I'd suggest a hardtail with long travel forks (130mm+). This will give you the option of hitting the gnarlier stuff if you fancy.
Personally I'd always go for steel for a hardtail frame, reason being alu is light but gives a very harsh ride and beats you up. Then again I'm only about 11 stone (155lbs) so these things matter more to me than a big guy like you. Steel does tend to be tougher though, and you'll want summat that'll last you. A good steel hardtail with decent foks weighing 28-32lbs should do you fine. I run a double chainring set-up (10 spd cassette = 20 gears) but you'll probably want a triple to give you tiny gears for climbing.
From the big US brands you can't go wrong with a Specialized or Trek, good value bikes. Don't know much about Norco (we've only had their top end DH rigs over here) but think they're pretty good.
Hope you have fun with your new toy. To me mountain bikes and motorbikes complement each other perfectly - riding a sweet singletrack trail is similar to riding the twisties on the T, difference being 120bhp -v- .0005 hampster power! I would suggest riding summat interesting though, if you go for a slightly technical trail you'll be having so much fun you won't notice the pain in your legs and lungs! I've been taking Windy out cycling (mtb and road) - he's a big guy but he's starting to keep up with me on the climbs!!!
Any advice on specific bikes needed give me a shout.