FreeS/WAN vs RealVNC

At the last Westside meeting I was introduced to FreeS/WAN and it
looked like a pretty cool VNC server. So I finally go to play with it
and discover that what yum installed was RealVNC from the original team
at AT&T labs in the UK. It also looks pretty cool and comes with free
Win9x clients which could be a real advantage.

So as anybody tried them both? Any advice on which to learn first?