A long time ago when XP x64 was being tested & no x64 drivers were available for my NIC card I just "decorated" a x86 driver & that worked fine on XP x64. It doesn't work anymore on Vista x64 since they fixed the unsigned driver bug, sure the internet will work (using the F8 trick) but MS updates are broken using that. For Win7 x64 I submitted a bug on the NIC driver & MS made one for that (onboard) NIC that works great. Making a decorated x86 driver is easy, but getting it signed & acceptable in Win 7 ain't.
its the other way around actualy, test driver signing always works, its the disabling signature checking thats been outdated since before win 7 rtm even... anyway, just check my thread as uri posted above
Can we sing ourself a drivers using a slef-signed certificate which we also put in the ROOT store of Windows? I do that with my Macro for Outlook. Icreate a CA (which is trusted on my computer) and I then create a certificate to sign my programs.