As my first official act as new Matrox forum mod I'd like to put together this thread with links to reviews of the P-series Matrox cards.
a Japanese review comparing benchmark scores of the P650 against a Parhelia.
Globetechnology.com has a concise 1-pager here
Of course TR did a thorough 15-page review here
Designtechnica.com does a good job in their review
Camcorderinfo.com has a somewhat short and uninspiring look at the P750 here
A two page review at Edgereview