Going back on topic for a minute, my macbook C2D with 1 gig Ram and the much lamented 950 does visual effects like the ripple on dashboard, where my g4 mini with a dedicated 32Mb ATI something or other does not. I also never noticed the little things like semi transparent menu's on the mini, where I see them on the macbook.
Which would lead me to summise dedicated != better than intgrated.
Also, the macbook is (afaik) the best selling Apple computer. Laptop sales are higher than their desktop sales. Laptops still ship today with the 950, leopard was originally due June latest, and hardware revisions are not affected by software revisions, as in, the leopard delay would not make apple delay a hardware revision. Therefore apple was originally intending to ship leopard on a 1.66 CD with 512Mb RAM and a GMA950 (the current low end mini). Therefore leopard MUST run on that.
Also I'm sure I've seen somewhere that leopard runs on a G4.
At the end of the day, the macbook is an incredible machine. it's very very fast. From any other manufacturer it would be a high end machine. With apple it's a low end machine purely because they start higher up that others in terms of quality of processor etc they use. If it'll run vista, it'll run leopard easy.