I can't say anything about the Mac side of things, but IMO, those Windows minimum requirements are way too low. They're almost asking for returns by posting such low specs and calling it "minimum".

Minimum, to the non-tech savvy, would seem to imply that they can use Poser if they meet those requirements. I can't see anyone actually using Poser with those specs though. It might technically open and run, but I think after that you'd probably do better to simply draw your own previews on paper. ;-)

Yeah, that seems kinda irresponsible. I'd at least double those numbers if I were them.

And what is "recent NVIDIA GeForce and ATI Radeon preferred" suppose to mean?
Some people may think "recent" means they have to go out and buy a GTX 260 or something. Of course if they're only on "minimum" specs, hell they might have a regular PCI or even an AGP bus for video.
I can see it now, "But Smith Micro TOLD me to get that video card..."

Not just that, but "recent" in terms of Poser is far different than "recent" in terms of the reality of what Poser can make use of. An 8800 series isn't particularly "recent" anymore, but due to Poser's OpenGL calls, a more "recent" GTX 200 series doesn't perform any better than the "old" 8800 GTS.
Unless they've drastically changed that for Poser 8, but all the accounts so far seem to indicate Poser 8's OpenGL ability is the same as Poser 7 and Poser Pro, or possibly even slower in some cases.

Quote -
Will Windows Vista even run on a system with only 512 MB RAM?  Huh.

Hell no it won't!
Which makes it even worse, as Vista is included in their list of supported operating systems.
I think they just copied and pasted the Poser 3 specs. ;-)