Microsoft is barring netbook manufacturers from utilizing hybrid storage solutions. Miniature notebooks housing both SSD and HDDs will not be permitted to use Windows XP, reports bit-tech. Redmond’s latest restriction will join the already enforced rule which limits netbook manufacturers to a maximum of 1GB RAM – that is, if they want to install Windows XP.

The news comes as a tough break for MSI, whose Wind U115 hybrid netbook has already hit the shelves. The device is engineered to dedicate its SSD to the OS while offering a conventional 2.5” 160GB HDD for additional storage. As a result, the company reportedly has until the end of June to yank the U115 off the market. MSI seems to be interested in remaining at peace with the software juggernaut, and will cooperate.

It’s also a bummer for NEC who recently unveiled their hybrid LaVie Light netbook in Japan. Vista is too resource intensive for Intel’s Atom CPU and Windows 7 is still 4-5 months away, so it looks like companies will either play ball with Microsoft’s XP requirements or fall back on Linux for their hybrid devices.