[KarmaKiller]

As far as RAM, that depends on what your getting that stuff for. You can always save some money most of the time. But IDK what your paying for it.

The only difference between those boards are DDR2 and DDR3. Other then that, it's essentially the same thing.

And for Hard drives, might check into these:
Western Digital's Caviar SE16 640GB hard drive - The Tech Report - Page 1
Newegg.com - Western Digital Caviar SE16 WD6400AAKS 640GB 7200 RPM 16MB Cache SATA 3.0Gb/s Hard Drive - Internal Hard Drives)



EDIT:
Apparently there are DDR2 X48 boards, so I guess I'm not sure what the difference is besides price.