<<Why would a manufacturer provide unsigned drivers for an OS that requires signed drivers?>>
I cannot answer that...but I can say that unsigned drivers are not a big deal on XP or Win 7...they work. I have no idea why Microsoft seems to think that digitally signed drivers are so important...when they build a bypass of the unsigned notification into every version of Windows. I've never thought it important, since I know that unsigned drivers work as well as those signed, as long as they are the correct drivers from the correct device manufacturer or OEM (HP, Dell, etc.).MS Says...
This would lead me to think that MS places emphasis on signed drivers...because it thinks that system users are not smart enough to obtain drivers for the components from the proper source...which is partly true
. There are websites that offer "drivers" that may be malware...there are software programs that users employ rather than obtaining the drivers from the obvious reliable source...and I suppose that MS is trying to protect these users from themselves.
But, as I said...every version of Windows allows users to forego the "unsigned" notification, so it appears to me that someone at MS thinks this notification is a good idea while someone else (with greater clarity) decided to implement ways to ignore/bypass the notification.
<<The old HDD was 320G, and the new one is 500G. Any chance that could make a difference?>>
If you are asking whether hard drive size makes a difference to the OEM recovery procedure...I would guess not, as long as the new drive was capable of a partition at least as large as the old drive. I can't really say because I've never had an OEM system that uses recovery disks, but that just seems logical to me.