I've noticed on my laptop that the CPU is working a little harder under Windows 7 than it did under WinXP so the higher temps with the same cooling solution would stand to reason.
Lately, with the larger CPUs, I've not been real impressed with the stock cooling solutions. They seem to be an almost afterthought. The stock solution that came with my i7 is a good case in point (see attached)
The black plastic shows the size of the integrated heatsink of the CPU chip. Compare that to the size of the heat transfer surface on the stock cooler - it's clear that about 30% of the cpu will NOT be in contact with the cooler.
Using this cooler
(with an appropriate 120mm fan) I have yet to see temperatures go above 109°F/43°C even while ambient temperatures are hovering around 80°F/27°C: