Vista SP2: Win Update or executable installer?

This was posted elsewhere, sorry.

I have a fairly slow broadband connection (1 mbps) but barely good enough
for downloading Vista SP2. However,
considering efficiency and reliability, would I be better off downloading
the standalone installer (using another faster connection elsewhere) and
bringing the download on a flash drive to my computer?

Is this standalone installer much bigger, containing irrelevant stuff, than
what Windows Update would eventually supply me with (since I'm current with
all previous updates)?

Thanks.

EW