I have a 24inch LCD and I'm very happy with it.
I can play most games at the native resolution, however, anything now will struggle.
If you are a gamer, you should know that gaming is best at the native resolution if it's an LCD.
The 2560x1600 native resolution of the 30inch beasts out there isn't exactly going to run very well unless you plan on spending $400-$500 every 6 months or so on a
new video card.
I recommend dual 24inch screens, because you can get away with spending about $250-$300 every 12 months on video cards, and still play games at the native resolution.
That said .... AFAIK 22inch Monitors are out now, and they often cost less than 1/2 of a 24inch monitor.
Unfortunatly, the
Matrox TripleHead2Go
Does not support triple 1680:1050, (and even if it did, I don't think even an 8800GTX could handle that resolution and get a decent frame rate in modern games with settings turned up.)
Perhaps your optimal setup would be 1x 24inch LCD in the middle ... for games, then 1 22inch LCD in portrait mode on each side ... you'd probably need to pick up a secondary low end cheap video card to connect the third display to ... but it would be pretty easy to get.