Homeworld 2 comes with a limited number of standard, selectable resolutions (640x480, 800x600, 1024x768, 1280x960 and 1600x1200) all with a 4:3 aspect ratio. While a lot of PC manufacturers had been selling PC's with LCD monitors for a little while or were beginning to when HW2 was released in late 2003, LCD monitors (mostly 17"-19" 1280x1024 - 5:4 AR) and more recently large 20"+ widescreen (16:9 or 16:10 aspect ratio) were not nearly as prevalent as they are today, so HW2 seems to have been designed for a 4:3 aspect ratio. Indeed, while many current and upcoming game have provision for native widescreen support, some current titles still have minimal or even no support.
However, it is possible to manually select other resolutions by adding some text to the properties of the HW2 shortcut, along the lines of:
"C:\Program Files\Homeworld2\HW2.exe" -width 1280 -height 800
There should be a note in the HW2 readme.txt about this, so if you want to try it out, check the readme. I tried out some non-standard resolutions when I was testing the mod -- the only issue here is that the game and interface look stretched in widescreen resolutions, but it should still work. I tried 1280x720, 1400x1050 and 1920x1080. Other 4:3 resolutions like 2048x1536 or common laptop resolutions like 1280x800 should also work.
EDIT: Just saw your update. The Scimitar addition looks great -- it's amazing that you can just whip something like this so quickly!
As you said Aaron, the UBW fighter inventory is quite competent, but I wouldn't mind the Scimitar's inclusion -- perhaps to spice things up it could limited to being built from UBW cruisers or space stations? Or maybe it could have a specific role? Anyway, really cool bit of work!
Cheers,
Bryn