Matrox TripleHead2Go vs SLI/Crossfire

SLI / Crossfire have nothing to do with displaying on multiple screens. They are simply terms for using more than one video card at a time. They add extra power, not extra screens. What you're thinking of are EyeFinity (ATI) and SurroundView (Nvidia). Either card that supports one of these two technologies will allow you to use all 3 monitors. ATI has been supporting EyeFinity since there 5xxx Series cards. Any recent ATI card should be capable of this, the more powerful the card the better. With more recent driver updates you can use monitors that are not the same resolution but the higher resolution monitor will drop down to match the other 2. For Nvidia. there latest 6xxx series cards support surround view allowing use of 3 or more monitors depending on the card. From what I've heard SurroundView isnt quit as good as EyeFinity yet. Personally I've been running EyeFinity for several years now and love it.

As far as TripleHeadToGo. AVOID it, its old tech. Triplehead was the way to go before the manufacturers started supporting the feature by default. Triplehead would connect to one input and basically allow that one input to output a high resolution which the triplehead than does the work of splitting between the screens. It doesnt allow as high of a resolution and tends to have a lot of issues from what I've heard. They were great back in the day when they were the only option but now with modern video cards supporting this feature by default the tripleheads should be considered a thing of the past.

There is also a 3rd solution available called SoftH. Great piece of software, but can be a PITA to get running properly. It would even allow your middle screen to be a different resolution than your other two. I believe it requires 2 video cards though unless something has changed in the years since I've used it.

To know which solution is best for you we would really need more information. What are your system specs, especially your video card?