Right, I've read about portaling & how the engine only renders say the inside of a room if it would be visible from that perspective. Guess I'll have to read-up on the other areas also. Just wanna make my map & not have to read more than necessary, but it looks like I'll have to invest more time into reading.

Experiment, make a basic map, maybe a couple of buildings in it and try out various techniques, also some of the best portalling help that I have ever come across was from the makers of the game themselves, not sure if COD4 has one but COD2 had some good help files.

IF you have COD2 installed with the tools::

cod2 help file:: file:///E:/Games/Activision/Call%20of%20Duty%202/Docs/portals/portals.htm

(just change the directory name "E" to yours)

Actually, this is the 1st COD game I've ever played. It's also the first map I've ever made, other than some test maps to learn the skybox & custom textures. It's great fun & I learn something everyday I've worked on the map the last 2 weeks. This is a great site with helpful people..=) Reason it's taking as long as it does is taking all the measurements in 3d mode in the other game & then creating everything from scratch in radiant. I'll let you guys know when I have it done if anyone wants to check it out. Thanks for the help.
If I create objects in maya & import them into radiant, does it count as only one brush?

It would probably count as only one "xmodel".