I will update this when Hammer is Patched.
To start, you need to find your Hammer.exe
To do this, go to Steam/Steamapps/username/sourcesdk/bin/enginename (orangebox or ep1)/bin
Find hammer.exe, and make a shortcut of it.
Put this somewhere you remember, like the desktop.
Open up Properties and find the Target input.
add -dxlevel 80 to it.
The reason Hammer is buggy, is because the Direct X level is set to 90, which doesn't work.
This fix is a bit buggy, but it's better than having no working SDK at all.
Here's the bugs...
-Model Viewer doesn't work right
-Entity Names and Brush Sizes aren't labeled in the 2D Views
-Hammer Crashes a lot, for no reason, it's probably due to something stupid in the system
Those are the only bugs I know, message me if you discover more.