i happen to know quite a bit about the d975xbx.
it's a great motherboard. it is a crossfire board. and the stability an intel board will give you will be outstanding. the "bad axe" will overclock as well, although maybe not as well as a lan party or something.
the bad axe supports core 2, as long as you get the right revision. i know 302's work, but i'm pretty sure that is only with a rework, so you might look into a 303 or 304.
crossfire is nowhere near as mature as sli, but i feel this day and age either is still unnecessary, unless it's for an upgrade path. often times people spend more money to get a lesser sli/crossfire rig than would be cost-effective to just get a better video card. a single x1900 will outperform many of the lower models, same with the 7800 and 7900's, so watch what you're spending.
if ati's physics platform comes to life, any dual-pcie board would be just fine to run graphics+physics.
stay away from raid0 unless you _really_ need it. you would be better off with JBOD, which i believe the onboard intel matrix storage supports. the only time i would consider raid0 is if you need serious speed for LARGE file transfers, ie pushing around gigantic files with video editing or databases or something. the performance for typical usage is hardly noticable (if at all), and the data is MUCH less secure.
and, if the matrix storage doesn't do jbod, i'm sure the additional sil sata controller will. the matrix storage controller will do raid 0,1,0+1, and 5 just fine.
hope that helps.