If you use the search facility it all becomes clear
To use a barton xp in an MP board you need to fill the last LV5 pit, then up the multiplier (17x is quite good). For the mobile cpu's you need to cut the 4th bridge (disable mobile cpuid). then also change the muiltiplier by pin modding. I have 2 x 2500+'s xp at 2.266 and 2 x mobile 2500+xp's at 2.266 (need to up the multiplier to 18x).
Personally I would (and did) by the Mobile xp's as its easier to mod them, and use conductive paint on the pins to mod the multiplier (better than the wire). Performance is pretty nippy.