Hey Mambwe:
I too am interested in the Trek 4900. I ordered one almost 2 weeks ago, and it has not shown up yet! I'm going nuts! It will be my first "real bike" as well. Paid $550 for it.
I am 6'- 2", 250 lbs, and am going to ride it the same way that you described... I hope I don't find out that I made a bad decision. The LBS assures me it will hold up.
FatBoy