If you'd rather download the service pack manually, you can do so via the Microsoft Download Center, which notes that SP1 works for both Windows 7 and Windows Server 2008 R2 (which it does). There are a number of downloads listed on this page, so don't be confused. The ones you are most likely concerned with include:
DVD image with both 32-bit and 64-bit versions of SP1.
The file named 7601.17514.101119-1850_Update_Sp_Wave1-GRMSP1.1_DVD.iso can be used to create a DVD that includes an interactive Setup routine that will install SP1 on both 32-bit (x86) and 64-bit (x64) versions of Windows 7. This file is 1.9 GB in size.
Interactive installer (32-bit).
The file named windows6.1-KB976932-X86.exe can be run on any 32-bit version of Windows 7 to upgrade that system to Service Pack 1. This file is 538 MB.
Interactive installer (64-bit).
The file named windows6.1-KB976932-X64.exe can be run on any 64-bit version of Windows 7 to upgrade that system to Service Pack 1. This file is 903 MB.
Note that Microsoft recommends that you follow the instructions in a KB article before you install Windows 7 Service Pack 1 from the Microsoft Download Center. The important bit here, from what I can tell, is to ensure that Windows Update KB2454826 is installed first. If you install SP1 via Windows Update, it will check to ensure this update is installed first automatically.