Which bike for a newbie?

1) your physical size 6'1 250
2) How physical / aggressive are you ? I would ride pretty hard
3) what do you plan to ride- trails, fields
4) Do you have any riding experience? 4 wheelers thats it
5) Do you think you will race ? NO
6) Are you mechanically inclined and will you be doing your own bike work? I could do most of it probably
7) Do YOU have a preferance to a brand/ motor choice (2 or 4 stroke)? From what I have read so far a 4stoke maybe a Yamaha?
8) Do you have a dealer close by your home that you might use and what brand(s) does he carry? Yes I do
9) How much ($) do you plan to spend on a bike? not more than $1500
10) Do you live in California? Nope, Kansas
11) Your age?22
12) anything else that you think would help form an opinion? I just want something I can ride around on our farm with and go riding with some friends

Forgot to mention a buddy has a 01 Yamaha YZ250F that he would sell to me in my price range.

So will a 250 be something i'll have fun with for a year till I get comfortable with then want something that will go faster, or will this hold me pretty good?