Hi:
Alternatively, you can use manual update by running Windows Update and also
to click "more information" link of each update which in most cases would
redirect you to another page which you can download each file.
There are many possible causes that your download may not start or take so
long, such as the site is busy, your connection problem, and so on and so
forth.
For SP2, the file size is large and there are thousands of users are
downloading each time.
So my suggestion is that you may try to download those updates (especially
SP2) to your local drive and perform installation from there.
Hope this will help and good luck.