Windows 7 oem is on sale for $85 at newegg. Is it legal to buy and install this? I see that it says you must buy it and install on a pc that you are going to sell. I am not going to sell the pc. I am going to keep it. Is this a difficult process to install the oem? It says you must install your own windows 7 drivers? What is the process for doing this? Should I just buy the regular version?