Download Windows 7 and Windows Server 2008 R2 Service Pack 1
If you have a bunch of machines you want to install SP1 on you can always use Windows Update. This means however SP1 is going to be downloaded over for each of the machines. Obviously not if you’re using WSUS!!!
In my case I have a lot demo machines in hyper-v that don't have access to the internet and I also have a bunch of laptops and servers at home.
Simply go to Windows 7 and Windows Server 2008 R2 Service Pack 1 to download the 32 and 64-bit versions of the service pack.