http://www.notebookreview.com/default.asp?newsID=2903
http://www.reghardware.co.uk/2006/04/04/review_fs_amilo_pi_1536/
The Register's review says the RAM is dual channel; the Crucial memory configurator disagrees.

It appears the same chassis is used by the Alienware m5500 range; the T7600 and 256MB NVidia GeForce Go 7600 version is tested here.
Also the Rock Pegasus 665, mini review at Pc Pro for a similar T7200 + GeForce Go 7600 setup.
My guess at the original manufacturer would be Uniwill as their p53ia (ATI) and p53in (Nvidia) are very similar in looks and spec. I do not recommend updating the BIOS from Uniwill, though.