Hello Brian,
As you see Vista SP2 contains all the updates that were released since SP1,
so by downloading via AU (Automatic Updates) you only get what you need, by
downloading the full file you have everything plus you have it if you want it
for later if you require it.
For Service Packs, I prefer to download the full file and then install
offline after preparing the system first.
Methods to download the latest service pack (VISTA SP2)
Method 1: Turn on Automatic Updates (Recommended for most users)
Method 2: Check for updates on Windows Update (Same as Method 1 but not
automatic)
Try Method 3
Method 3: Obtain the latest Windows Vista service pack from the
Microsoft Download Center (the full file)
<
http://support.microsoft.com/kb/935791/#Method3>
(Good to use if the computer on which you want to install the service pack
is not connected to the Internet)
Go to <
http://technet.microsoft.com/en-us/windows/dd262148.aspx> and look
at the left side.
Things to know about SP2 and FAQs.
Review them thoroughly and see if that answers most or all of your
questions.
If not, repost here.
You will also note the download site available for the full download which
can be used instead of the Windows Update service.
Free unlimited installation and compatibility support is available for
Windows Vista SP2 issues until August 30, 2010. Availability of chat or
e-mail support differs depending on your geographic location. Some issues
may require more advanced support for which there is a charge. Go to
http://support.microsoft.com/oas/default.aspx?prid=13014&gprid=582034 &
select appropriate category (i.e., Download issue; Installation issue;
Issues after you install a service pack).
Good luck
-=-
