Those of you who have played the game Star Trek: Bridge Commander know it has fucking SPECTACULAR visuals, and that the Quick Battle feature will let you pit anything in the game against practically anything else.
What you may not know is that this is probably one of THE most moddable games out there. www.bridgecommanderfiles.com has dozens upon dozens of downloadable ships, plus downloadable bride environments, crewmen, retextures and upgrades you could stare at until your eyes fall out.
For you vs. fans, they have B5 and SW ships.

This brings us to the aforementioned battle between GCS and ISD (Somewhere between Luna and the Spacedock in Earth orbit, of course.)
The fight was great to watch, if technically very inaccurate -- the ISD didn't really do much of anything except hang out and absorb phaser fire for about five minutes before lazily smacking the GCS. I would have expected something livelier.
Another complaint about the ISD is that it appears to be scaled too small -- it's only a third larger than the GCS, from what I could tell.
Still, minor complaints aside, this was the coolest thing I've seen on any screen in a long time. I highly recommend you check it out.