Microsoft has recently released windows vista service pack 2 (SP2), It can be added to your vista operating system through standalone installer package or via windows update.
The size of the 32-bit standalone package of vista service pack 2 is around 302 MB for the five language and 390 Megabytes for the seven language service pack. However it takes less bandwidth when you download and install vista service pack 2 through windows update.
Here are all the direct download links for Windows Vista Service Pack 2
Download Vista SP2 32 bit Version | Download Vista SP2 64 bit Version | Download Vista SP2 DVD ISO