Hi Evan, Couple of generic comments on your choices. When planning a Linux box it is generally better to buy last year's best hardware rather than this years. If you buy the latest and greatest video card you may find that your Linux doesn't support it.
Same comments apply for USB peripherals.
I've got a UMAX 1220U scanner on Becky's iMac and like it just fine, but I don't think I'd get one for a Linux box.