The HL2 update to the Orange Box engine comes with a number of bugs, and it’s incomplete. The mod I linked fixes all that.
Half Life 2 comes in the Orange Box, but wasn’t on the Orange Box engine (aka 2007 engine). Valve recently updated it so that it ran on that engine.
It was the guy’s website, but it might have been linked through HL Improvement.
Edit: I did find it through HL Improvement! link
IIRC they didn’t have everything in there, but they had a lot of stuff, and you could use the HD pack for the rest. (not the Steam version, it overrides any custom models, get this and if you plan on using it in Blue Shift, this.)