We're not quite sure why Sony decided to use a different CPU for its Vaio P not-netbook in Japan, but for whatever reason, the Japanese are getting an Atom Z540 clocked at 1.86GHz rather than the 1.33GHz Z520 processor found in the Vaio P in the US and Europe.

The extra 530MHz seems make a difference as well, at least if the benchmarks we spotted on Impress are correct. The Z540 seems to be almost on par in terms of CPU performance with the Atom N270, at least in PCMark 2005. The tested model had one of Sony's 128GB SSD drives and it seems like Samsung is the manufacturer. Unlike other netbook SSD drives we've seen, the one Sony is using is screamingly fast in comparison, as it scores over 11,000 points in PCMark 05.

The US15W chipset doesn't seem to be a match for the 945GSE though, although we're not sure at what resolution the 3D benchmarks were run at. Even so, the graphics scores aren't too impressive, but then again, the GMA500 was never meant for heavy 3D graphics.

You can find a screenshot of the 1.86GHz CPU here and some benchmark details here