Beginners bike?

I think you will probably be ok with the power,if you keep your forhead and right wrist connected (something I have the occaisional problem with) I would be more concerned with the ability to keep it running well. If you are pretty well mechanically inclined O.K>, if not the XR and KLX will probably take much less work to keep in good shape. I have a friend with an XR400 who is absolutely scary with tools and his bike hasn't missed a lick. Must be a really strong design.(just kidding Hal)
:debil:

get a used KLX with all the right mods done to it (search Thumper Central), or Xr400 (heavy, though). Reliability is a very valuable thing when on the trail. I've found that performance matters a lot more when you're bench racing. Having a bike that needs repair sucks (been there). Not to say there aren't reliable Husabergs out there- or XR's or KlX's that break down- just seems to be a general consensus. I even had a blast on an old XR200 not too long ago (it sure beat sitting at home!!!).

Enjoy riding. First bikes should be a source of enjoyment, not frustration. :)