This time by HardwareZone :
By far our two favorite features of the Parhelia are its 16x Fragment Anti-Aliasing and TripleHead function for Surround Gaming. The quality-to-performance ratio of that anti-aliasing method was pretty good. But it does come with one noticeable limitation. While it does take away a lot of the "jagged" edges of an object, the overall image quality isn't as well-defined as NVIDIA's 4xFSAA or even Matrox's own 4x Super Sampling (SS). That said, while Matrox's 4x SS anti-aliasing churns out some of the best images around, the miserable frame-rates incurred means that you're definitely better off with either 16xFAA turned on or none at all.
DualHead? No TripleHead!