windows update doesn't work

okay at first this wasn't too anoying but now it is a major problem

at first it was just that when i went to windows update it would get stuck in the thing where it says that it is checking for the latest updates.

to try and solve this issue i did these things:
-i ran windows update for 3 days straight and didn't do anything on my computer (it was stuck in the screen i mentioned before)
-i reinstalled windows, but for some reason the problem carried over

a friend of mine told me about windows defender and that it was free, so i installed it and behold it uses windows to update and im stuck with the bare bones of the program.

recently i tried to install the newest internet explorer, but that requires windows to check for updates, so it didn't work this i could deal with but the next thing was the last straw.

when i recently purchased my zune i went to install the software, giddy as a school girl and blam! it smacks the update on me, so now i cant install zune marketplace.

okay baisically i just want my windows update functionality back cuz its really starting to bite me in the -blam-, so just start throwing suggestions at me cuz ive tried everthing i can think of, thanks in advance

Make sure the date on your computer is correct.

serivces.msc: start up the following services and make sure they run: automatic updates, cryptographic service, background intelligent transfer service (bits)

create a new user profile on your machine from compmgmt.msc and see if you still have the issue

safe mode with networking will not work so dont bother

ie7 install has an option to skip the update section, or just unplug your network cable, once it fails to retrieve updates it might just bypass that step

firewalls can cause issue this and so can routers, since you say you formatted and still had the issue, see if you can plug your computer directly to the cable or dsl box that you have to bypass any hardware firewalls and routers

this is the latest internet explorer update, apply it and see if you still have a problem: http://support.microsoft.com/kb/922760

on internet explorer, click on help, about internet explorer
make sure the cipher strength is 128-bit

disable any anti-virus software you may have