Ill 2nd what suiken_2mieu has to say, I am also running tri screen games using the sothTH method, personally I do not notice any lag in any of the games I run, everything is synced.
However this method is fairly taxing on the system and thus may suffer with lower performance pc's.
As for what games you can expect to run on your system take a look at the
games list (at time of writting the main wsgf navigation links appear to be broke and take you to the main page only) and the
detailed reports.
In short, as you may already be aware sothTH only has support for DirectX at present, and thus any openGL games will not work.