the mobile barton is the notebook cpu, it has a 1.45 core voltage ,but it will run at the higher core voltage @ less temp
the normal barton has a 1.65 core voltage and is now a locked cpu (most will still overclock to 2.2 ghz though,which is plenty and the most stable for it)
just do a google seach for a 2500+ mobile barton and there you will find it .. I got my last one at mwave for 75 plus 6 dollars shipping.
If your not planing on clocking it to run at 2.0-2.2 ghz then the stock heatsink fan will probely work . (providing that you have a good side case fan blowing "inward" to help it out )
there are some good hs fan combo's for around $20 that will keep a 2500+ cool at 2.2 ghz .(beshure you use artic silver or another "Top" of the line thermal compound) use just a raindrop worth on the center of the "die"
As for your set up it looks fine .. I would suggest a nvidia video card if your not to familier with changing drivers and tweeks though . ( I have 3 nvidia's and 2 radions at the moment and the nvidia's always are easier to work with ,and they like ah2 better )
one thing to note is ah2 is a picky game on the higher end pc's and when looking for hardware setups were still in a trial and error basis .