If you want to breath life into homeworld 2 and get away from the oh-so predictable ship build lists, try out PDS.
Webby here
I could recommend you an install version, but as the mod seems to have about 12 different 'current' states, I'm afriad I can't. Basically one version (should be 7.3, PDS 'classic') has stayed true to the old ways of homeworld but activated the already present point defense systems on almost all of the ships, whereas with later versions the designers seem to have gone down some harpoon style gameplay which doesn't really fit with the engine.
Basically everything has been revamped for better balance/immersion and a visual FEAST. A couple of new style (7.3-ish) heavy fighter wings would be able to eat almost any old style ship for breakfast, even the smallest ships have got PDS etc and longer range/more powerful beam weaponry. The latest arbiter, for has maybe 9 turrets, 4 missle/torpedo racks and then the PDS systems as well. The newest vagyr battleship has weapons based loosely on Sajuk (sp) etc, but would easily be able to wipe it out.
Don't get me started on the new torpedos either. The first time you hyper-gate a fleet of 20 Vagyr heavy missle frigates in at long range behind a Hig battlestar and you watch their bay doors open and unleash guided missle death on the massively expensive hig fleet command ship (and their only means of hypering out of there) you won't be able to do anything but laugh.
If you liked HW2, I'd recommend you give it a shot, but you'll need a mostrous comp to run it flat out in big fleet engagements.
The main guy has now gone over to Warlords I think, so the gameplay may be similar. (haven't tried warlords yet)