I'm nearly ready to go and buy one of these little machines (dm1-4004sa/4027sa), but I just want to be sure that I have the right tools to change the machine from Win 32 bit to 64 bit (I do understand this requires a fresh install), without buying a new Win 7 licence. People have previously posted that they've had no problems doing this with an OEM Win 7 install disc. I have an external USB DVD RW drive and the Win 7 64 bit install DVD that came with a copy of Win 7 upgrade that I used on my old laptop (so that licence is now linked to that machine). Would this disc be suitable to make the change (has anyone done this with dm1-4004/4027) or do I need an HP OEM Win 7 disc (if so, does this come in the laptop retail box or do you have to download it from somewhere)?