Oh excellent! I'd hate to have had to been That Guy who doesn't buy something they really quite wanted on general principle, but hell, I would've taken that hit if I thought it'd demonstrate to Valve that making people buy the same game twice is naked lunacy (and not the fun kind).
Thing is, I'd definitely buy Portal. The concept is an absolute riot, and it looks like it's been deliciously implemented; I'm really looking forward to experimenting with all the ways I can mess with the fabric of reality with that gadget. I'd probably buy TF2; I love the art style, and I enjoyed the hell out of TFC, but I almost never play shooters online these days, because, well, the internet is full of wankers, basically. I might buy Ep2, but I've not played EP1 yet, so it wouldn't be for awhile yet. Portal is the dealbreaker here, essentially, so I'm glad I can choose to buy it alone if I want to.