There seems to be so many 1000s of people having the same problem, I would think
the Arduino development team might look into this, and either find a way for better
software driver installation, or else come up with a more bulletproof uploader program.
Maybe one that has some option settings.
Also, I think the problems have become worse with the newer R3 boards, ie, new
drivers, larger upload packets, and faster transfer baudrates.
One thing to try is see if the driver for the board is installed properly .... go to
Control Panel > System > Hardware > Device Manager, and see if the board shows
up in the Ports section when you plug and unplug the board.