Multichannel video – synchronisation

I’m looking at technical solutions for doing multichannel video projections that are synchronised (incl audio).  What are the basic approaches and are they affordable?

Playing two or more videos from a single computer – matrox dual head and triple head

Synchronising multiple computers playing each channel – network software from Zach Poff (and much more)

Using brightsign HD players ( normally used for digital signage) for multi-channel installation.

The cheapest Brightsign player LS423. This is recomended by ZP.