DON"T UPGRADE!!!!
Create a separate partition, or install a new disk, and perform a clean installation.
Why???
So your current, stable, happy system, continues to be available.
Putting w8 on its own partition means you can learn, configure, and test.
And most stupid: MS is not releasing a stand-alone upgrade advisor. The advisor is available when performing the upgrade!!! Way annoying.
Main problem here is cannot print from the w8 machines.
HP printer attached to w8, installs, is found, can be configured, no printing.
Brother MFC on shared on w7 comp, w8 finds, installs driver from windows update, can be configured, no printing.
One user received a message from Canon that they will start providing drivers when w8 is released.
Lots of messages at the MS forums about printers, and cameras, and other hardware issues: the vista period??