I am not looking at this from a technical point of view, but from a marketing one.
I of course know all about the work done to try and overcome the problems (reported in various forums that can be navigated to from the Witcher's official site).
My take is that I am not blaming a small brillant team of polish youngsters with obviously limited resources. I am blaming Microsoft from not sending asap a high powered team to Warsaw to get the problem fixed because of the huge backlash effect this has on influential power users.
In fact, instead of competing with games developers with dubious properties of their own (nothing interesting IMHO since Age of Empire), MS should subsidize inventive studios coming up with landmark games to make sure they come out reasonably free of Vista-related bugs, particularly on the most state of the art hardware configurations. (I run The Witcher, and Crysis, Oblivion, etc... at full resolution on the Dell 30 monitor.)
Intel and Nvidia make it possible with their latest hardware and drivers to run stunning pictures at 2680 x 1600 with high frame rates. There is no reason Vista 32 (I am told the problem does not obtain with XP and Vista 64) makes these efforts crash on most saves.