@JoannaK,
Have you tried the Parhelia yourself ? Or are you basing it on some reviews ? The speed difference compared to a GF4 isn't that much, and like Mad-Matt sais, the framerate doesn't drop when using 3 displays... Playing Quake III, Unreal 2, Wolfenstein, Jedi Knight is in 1 word great, people should try it sometime... I wouldn't call a framerate of 90 vs 100 FPS underpowered. Besides, the screen display is supperior and having your desktop 3 screens wide is a real bonus...Just hate to go to work and use a big 19" (CRT) screen when I at home I can use 3 15" (TFT) screens :-)
I do hope however that like the Dual Monitor feature all cards "took" from Matrox, that tripple head will make it's way to the big boys (ATI/nVidia) someday..