Ugh, do I have to repeat myself? I don't really see the need for future incarnation of Construct to constrain itself to older platform which already is covered by current release.
I mean, are you going to buy a new car that is just as fast, albeit a little more efficient as the old car? Or are you going full out and buy a new model of the car, that'll go even faster and further?
Another example: Are you going to buy a P4 computer over Celeron? Or would you rather buy a Quad-Core?
Let's think ahead here a little... multi-cores are getting cheaper each month, even I could affort myself a dual-core AMD Phenom and I'm one of the most strapped with money around here. This machine runs Windows 7 without a hitch; heck, RC worked well on old computer anyway, which was Celeron 2.4 GHz.
In Construct's case, we can't afford to keep making small steps while everyone else is far ahead of us and gaining.
Construct 1 for XP, Construct 2 for W7/modern platforms. Hell, Construct 2 could feature even multi-threading support, how awesome would that be?