Yes, it’s installed in the x86 folder.
Because the 64bit version was never really maintained, so any problems from 2005 are still there. Valve rushed the 64bit version of HL2 because of WinXP 64bit, it was all the rage back then to have 64bit on the box.
I know that not everyone experienced problems, but a lot of people did (and still do). Regardless of that, even if you don’t have any glitches it doesn’t really have any benefits. 64bit programmes are supposed to be a bit faster, and this one just doesn’t have that.
Valve themselves have admitted that the 64bit version has its problems.
Anyway, I’m gonna install from my HL2 CD so I guess it’ll be the 32bit version after all