Update:
I updated the machine, minus a new video card. It seemed to accept Win 7 64-bit and 8 gigs of 800 MHz RAM easily and is running great.
Today the Sapphire 6570 video card arrived but did not fit, ironically because of the PCIe combo riser. The Web description of the card said 6.65 inches long, a shade less than the stock card. But in fact, the card is 7.25 inches long, and because it mounts parallel to the motherboard it conflicts with the CPU shroud. If mounted perpendicular to the mobo it would probably be OK.
Maybe the Sapphire will now go into the Mini Tower if I don't return it.