The B800 from Intel is a processor based on the Sandy Bridge architecture and features two cores capable of handling two threads. Like Intel B940, B950 and B960, it also comes with HD graphics 2000, instead of HD graphics 3000 like in case of Core i series processors. TDP is also the same at 35 watts which is why it is used in entry level notebooks, not ultrabooks (because of heat).
B800 runs at 1.5GHz clock speed and supports 64 bit operating systems and VT-x hardware virtualization. Turbo boost is deactivated like in case of Core i3 series processors.
In the Passmark test, the B800 got 1509 points which is considerably lower than Intel Pentium B950 and B940 which got 1982 and 1978 respectively. But, that does not mean that it is underpowered. In real world, it is good enough for view 720p videos and would not lag in multitasking and Photoshop, unless you are editing really high resolution pictures.
The above chart shows how it compares with AMD MV40, B950, B940 and Atom Z670 processors.
Intel Celeron B820 benchmark