SigBrowser Download

There's no Windows port. You need gtk2, a working OpenGL / glX implementation (works fine with nvidia's drivers) and gtkglext to run it on Linux or Solaris. Don't complain about bad performance without proper hardware acceleration.
On a Gentoo system you should get the neccessary things by running emerge -na gtkglext. Of the HW accel you have to take care yourself. Search google for howtos.
Use gcc 3.3 to compile it. I haven't tested it with other versions.