Why don't you use the proper method of updating and use Windows Update, or at least read official documentation like the link which Chris4 posted?
Some SP1 packages needs several other updates to be in place before you can install it.
And SP1 also comes in different 'flavors' (to make it all a bit more complicated), eg: you have standalone packages, packages which don't include other prerequisite packages, then there are different ones for different sets of languages, etc. Aka, one SP1 is not the other SP1!
try the official SP1 (all languages) package:
http://www.microsoft.com/downloads/details.aspx?f...-9D6D-50FE9461F808
Or Windows Update to properly install the correct package(s) you need.