If you want to play Homeworld and Homeworld: Cataclysm in a higher resolution than 1600x1200 (e.g. 1920x1080) without problems you have to run it in OpenGL.
If changing to OpenGL fails you have to run the exe in Windows NT 4.0 compability mode. Try changing it to OpenGL now.
After that, do this:
- Go into regedit
- Find key "HKEY_LOCAL_MACHINESOFTWARESierra On-LineHomeworld"
- Change "screenHeight" key to your screen height (800 in my case)
- Change "screenWidth" key to your screen height (1280 in my case)
- Make sure the "base" is in decimal
http://www.widescreengamingforum.com/node/5413
Works for me and for ma brotha ;-)
The game still looks gorgeous for its age in my opinion.