Windows 7 x64 comes with all sorts of signed drivers so there's high probability that all drivers for your machine will be installed during system setup.
On the other hand Windows Server 2008 R2 doesn't. Event though it's practically the same OS when it comes to drivers. I know there's a very good reason for this difference. It's a server product, not a desktop one. But the thing is that many power users and developers use server OS on their workstations which are usually desktop machines (a bit more powerful though) and would benefit from the whole driver spectrum that Windows 7 offers...
I know I've been reading on the internet about some trick where you first install Windows 7, than do something to get either all Windows 7 drivers or just those installed, and then install Windows Server 2008 R2 and use those drivers of Windows 7.
The thing is I can't find these instructions on the internet any more. If anybody knows where they are please provide the link for the rest of us.