For a guy that is just completely new to bikes, you want something that is easy and forgiving to ride, and something that does not require a lot of maintenance. If you are just going to poke around on local trails, climbs, and country roads, I'd look for an 02 to 04 Honda XR250R. (Its a 4 stroke that you can lug down to the last RPM and still go 70mph on) They are bullet proof, torquey, easy and forgiving to ride, require little maintenance, and can go all day in 5th gear on a gallon and a half of gas.
+ one hundred on What Buck said, now if you want something with a little more suspension try a new crf250x it is the trail version of the newer race bikes and has a better suspension than the XR but does require allot more maintenance.