If you're worried about the large download size, you could always wait until it is distributed through Microsoft Update. The download size should be dynamic at that point and it will only download the specific components you need. (Unless this behavior has been changed from XP to Vista?)
FWIW, SP2 was offered to me as an update this morning. 337.9MB - 343.9MB, not that much difference in size to the standalone version.
If you sit down and watch the 'downloading' process via WU you'll notice it isn't actually downloading very much even though it says it's downloading around 350MB. Mine appeared to downloading only in the realm of 100MB or so, and spent the rest of the time just verifying that the prior updates were in place. -- THIS IS SPENCER. MISSION ACCOMPLISHED - I HAVE JOE. RETURNING TO BASE.
