MSDE Rel A = 42MB, SP3a = 69MB!
Wow, I guess I was not paying attention when these came out... MSDE Release A is a 42MB download. It contains all the fixes up to and including SP3a. Service pack 3a for MSDE is a 69MB download. How strange. I suppose the difference is because Release A does not include merge modules.
Which reminds me of the Bob/Scott/Sean comment on WinXP SP2 RC1. The ISO for WinXP Pro from subscriber downloads is 489MB. The SP2 download is 475MB.