which bike?? please help

Ok im new to bikes and what to get one, the only problem is that im new and dont know which one to get. Im 5'6 150 lbs and have only ridden 125 once. I have ridden many sport quads before like yfz450 and raptor. heres a few bikes i found::03 YZ 125 aftermarket suspension, new chain sprockets.$3,999--01 CR 125, Bills pipe, renthal bars, pro action suspension, new tires, new sprockets.$3,495--01 CR 250 fmf pipe, twin air, renthal bars new tires, chain and sprocket, fresh top end. $3,600.--All prices are Canadian. Im not looking to race these bikes, only to ride for fun. Will the 250 be to big for me?

1) your physical size (both height and weight are important)5'6, 150 lbs
2) How physical / aggressive are you ?aggresive but not overly
3) what do you plan to ride- MX/SX tracks, woods, fields with friends or ?????trails, dunes
4) Do you have any riding experience?yes on quads, this will be my first on a dirtbike
5) Do you think you will race ?no
6) Are you mechanically inclined and will you be doing your own bike work?some of it
7) Do YOU have a preferance to a brand/ motor choice (2 or 4 stroke)?no
8) Do you have a dealer close by your home that you might use and what brand(s) does he carry?yes, all brands
9) How much do you plan to spend on a bike?$4000 canadian
10) anything else that you think would help form an opinion. i dont know if a 250 will be to big for me or not. i want something that i can have fun on and still be able to keep up with other sport bikes and quads



I also wanted to know if their are any major differences between a 2001 cr 125 and any of the new 125s

thanks for the imput. im still stuck on which to get though. the 125 seems like a good bike to start on but i dont want to be looking for more power in a year. The 250 might be a bit big for a beginner but i think i will get used to it because i have experience riding sport quads. i never thought getting a bike would be so hard