Okay so I am going to upgrade to windows 7 64 bit, I so far have made it through the upgrade assistant. Now when I put in the actual installation disk, in essence it tells me that this disk isn't compatible with my form of windows, blah blah blah blah. But then it says "to install a new copy of windows, restart (boot) your computer using the installation disc, and then select Custom (advanced). My question is how to I boot my computer using the installation disk?