I did a Vista install from scratch a while ago and the same happened to me.
Vista is now quite old (first came out 2006), and when it shipped it was not ready.
So since it came out there have been hundreds of Windows updates.
There have been early Windows updates, then later updates that go on top of them, then later updates that go on top of them and so on (as you are finding).
Rather annoyingly after doing all these updates it will then say you need to install a sevice pack, which is huge in itself.
So I am afraid you just need to keep installing updates and rebooting till it says there are no more.
You will then find Vista takes up about 40Gb (or more) of your hard drive - as it did for me (but there are ways of reducing it).