I installed on a very similar setup to yours: AMD 6X processor, 4GB RAM (two sticks, not one), 320GB SATA 2 hard drive.
Also had the default BIOS version -- FA, I think.
Took about a half hour to install Win7 32-bit -- nowhere near as long as yours. And, my drive is a WD "green" drive also, so I don't think that is the problem in itself.
But, unless the drive is brand new, I would suspect drive problems in it taking that long to install.
After install, noticed that the memory was set to 1066, so I upped it to 1333.
Downloaded a Gadget that shows the usage of the individual cores. Shows all six cores as being used. You might look into that.