...a fully updated Vista 64 in my opinion is a GREAT version of Windows, and my favorite version at present, although at some point failing security and driver updates will kill it. Not yet though, it is great right now.
Those who reflexively malign Vista have not tried it fully patched on stable modern hardware. It is a solid, stable, fast OS that all who pine for WinXP should try. I am running Vista 64 Ultimate on a nice slightly overclocked I7 right now. It is my "fun" computer. I own a Win 7 Ultimate full version disk set that I got for the future when I have to upgrade it (you have to use the exact same version to upgrade), but Vista 64 is the system I would rather run, so I am not doing that upgrade that until I am forced to.
Summary: Vista 64 fully updated = GOOD.
So, how to get VISTA fully updated?
FIRST, only do "Windows Update" and do NOT do "Microsoft Update" because Microsoft Update takes a LOT longer to check your computer for updates. Only change to Microsoft Update after Window is fully updated.
SECOND, you want to get it up to "service pack 2" (SP2) and then do whatever else there is after that. So ONLY do service pack 2 (SP2) update at first, and as a result you will not need a lot of the other updates. If SP2 has a prerequisite (I forget) then ONLY do that first (such as service pack 1 (SP1)) and it will save a lot of time.
THIRD, there is no doubt that Microsoft has changed how its Windows Update works: it has made it SUCK. On purpose. Punishment. For not submitting to Windows 10. Mostly it will work but it is very slow.
Moreover, one of the things I note is that Microsoft for all its liberalism [HYPOCRITICALLY, do ya think?] has decided that "illegal aliens" in its ecosystem must be punished. It checks IDs or you cannot fully access basic public services like Windows Update. In fact, it badly checks IDs, slowly checks IDs, even calls us illegal when we are legal, and DENIES us apparently second class citizens "the vote," only giving us bare minimum updates, really slowly, and not the other updates.
What I have found that helps is to be sure to have a photo-ID for Windows (unlike what Bill Gates thinks is OK for voting, nothing), meaning be sure Windows KNOWS that Windows is "activated." It forgets you much more often (now that their policy is to harass users of older OSs), thinking that your system or hardware has changed, etc. Go to StartMenu / ControlPanel / System and scroll to the bottom for activation status, and be sure that it indicates that your windows system is "activated" before you try to update, and it will work better. If not activated, waiting on that screen while connected to the internet can help, or clicking the link to activate can help, and sometimes you actually have to CALL Microsoft and they will activate it over the phone if you provide certain details like Product ID which are also on that page.
Other than that, it just seems like you have to wait a long time for updates.
I do not fully understands the thing you were doing with stopping updates with the task manager, but I will experiment with that if I face this type of thing in the near future.
Godspeed on this!