suggest me a bike

My Cylde rule of thumb is buy something 1 or two grades tougher than you use.
So for a commuter bike get an XC bike for XC get AM for AM get FR/DH.

The additional weight of the bike will be insignificant compared to the total; however the stiffness and strength of the bike will make a massive difference.

Kona Hoss/coiler are good starting points, but your budget is not enough for a good bike,

Maybe you could get a deal on a Rockhopper 29er.

i'm 6'3" and 270ish i ride a Jamis komodo. Techinically this bike is a hardtail freeride bike but I've been riding mountain bikes for a long time and even though this bike is heavy it is by far the most fun to ride, that I have ever had. In my opinion its perfect for someone our size and weight. The eight inch hydraulic brakes work great and it has wide rims too, which before i always had problems keeping my rims true, even running blackeyes on my otherbike (use to come on the Hoss). Now with the fat rims and 20mm axel it does'nt feel like a bag of mush underneath me. Also the frame sizing runs a big on theese. My 18 3/4 in is the equivelent of kona's xxl dawg deluxe. not sure if all jamis bike are sized like this but the komodo is.

The 2010 models are starting to come in so if you look around you may find some good deals on 2009 models. One of my local shops has Cannondales for $300-400 off the '09's.

yeah i am looking, just trying to decide, hopefully will be purchasing next week

I just bought a 2008 Specialized FSR comp. Buying the older model saved $400 and was close to your price range. Even though I have lost 35 lbs., I still weigh 250. I heard people talk about shock problems and wheel problems, so I bought from a local store where they have lifetime service. Took the bike on vacation and have riden many times since. No problems and love it. I plan on keeping the bike for a long time, glad I spent a little more.

Kona Hoss...no ifs ands or buts.