MS is not going to restrict anything at all.MS was FORCED to open the kernel source to competitive companies, so there is no way for them to "lock" in anyway the ring0 drivers.If it does something like that (it won't but anyway) gfx card drivers and similar stuff, will be useless, as most of their drivers are ring0 drivers.It doesn't make sense And Xtreme protector is too old to be an example for "unstabillity".