I used to have 2* Samsung 172x 17" screens :P
That specific model was advertised for the ultra-thin bezel, but it still was about 2,5 centimeters. It's kind of up to you if that's too much for using the screens in "horizontal span" mode (both displays doing the same game or movie or whatever) or not. Didn't bother me that much personally, though I'm not a huge FPS fan, I played Live For Speed and for that it was awesome. The wide picture with lots of mpix's let me see far more other cars than 1 display would.
I never had any kind of problem with the screens. Most games supported the dual-screen mode out of the box with full resolution (2560x1024). GTA: San Andreas being an exception. I never got it working (actually, if I recall correctly, that was the reason I joined WSGF!). Working games include HL2, Far Cry, Doom 3, GTA: Vice City, MS Flight Simulator, and virtually all older titles like RTC Wolfenstein.
I sold the screens recently though so no more dual display fun. Wanted a bigger screen you know. :P