i just tested out the usb tool from Microsoft by installing the Win7 64bit RC1 on my secondary partition. the tool worked well and can be used with most ISO files. i plan to keep a copy for installing other OS's as i find them and want to test.
ok, so i start d/l the student version of windows 7, and at some stage (as i left the d/l overnight) the progress has changed to -11000/22300K..... how on earth did it become a negative d/l.... meanwhile, checking my dl status, i have successfully d/l 2GB overnight, and into nothing????!!!
Here is the hilariously complicated Windows 7 Upgrade chart. According to this, you cannot upgrade from a Home version to Professional. You must upgrade to Ultimate or another Home edition. It's totally an artificial limitation and I don't think I understand the reasoning, but... that's the way it is.