I would not necessarily say that WHS is that much faster than linux. It really depends on the hardware and also the implementation of linux. Take for example the HP LX195 vs the QNAP TS-639. I know the QNAP costs quiet a bit more but I am looking at the base hardware. 1.6 Ghz Atom processor in both along with 1 GB of RAM in both. Similar hardware but one runs WHS and the other runs linux. The QNAP and HP are very close if you look at overall performance. I have seen similar results testing windows and linux at home on the same hardware.
00Roush