Duh, and it ain't getting any better. I get home late and at least want to download the SDK sources so that maybe tomorrow I get the chance to have a look at it. Turns out you have to download the frickin HL2 core files before you get the SDK (or something else). At least it said it would now start to download and install the SDK and that I need about 1.2GB of free space on the disk. Too bad the most space I have to spare is a few hundered MB, everything else is used up. Gnah!
Looks like I might have to go hardware shopping on the weekend before I get a first play with the SDK.
The guys in Bellevue aren't keen on making life easy for people like me, looks like it.