Hammer on Lowest Settings Humanly Possible?

I have a crappy, crappy, crappy computer. With that out of the way, the meat of the problem. ( If you're going to tell me to buy a new computer, I'm going to ask you to buy me one. Don't be stupid, stupid! )

I've been working on a map for quite some time now, and I figured I'd pop one of the Valve prefabs they recently shipped with the Source SDK update to see if I could feasibly navigate said map without too much frustration.

That map was 2fort; I couldn't navigate around the map in 3D view to save my life. Even disabling the auto groups and whatnot proved little help. What can I do to get Hammer to run decently on a computer that requires Quantum's Little Config (HighFPS) and TF2Tweaker in order to get a decent framerate in-game?

( This computer has a 2.93GHz Pentium 4 and a gig of RAM. It's really crappy. )

Alright, since I'm more or less boned until I can find a way to improve the program overall, what kind of changes am I going to have to make to the configuration file?

( I honestly don't care if I brick Hammer in the process; if I do that, I'll just reinstall if need be. )