I have just downloaded Windows 7 and Windows 2008 R2 Service Pack 1 from MSDN. It should also be available on Technet.
The download is a 1.75GB ISO file, containing the installer, and the Service Pack .exe files for 32 bit, 64 bit and Itanium 64 bit.
Installation on my HP DV6 laptop (5.5 Windows Experience Index), from a USB key, went on for about 45 minutes, with a couple of reboots.
You can install it even if you have Internet Explorer 9 Release Candidate in your system.