Many Firefox users complain that update.microsoft.com allows only IE to check for and download updates.
Not true, with the IE tab, you can download Windows updates easily.

Download the add-on here
Code:
https://addons.mozilla.org/en-US/firefox/addon/1419
Just open google and type
You Must Be Registered and Logged On To View "URL" BBCode Contents...
, on the results page just right click on the address and select "Open in IE tab" and it will open a new tab with an IE symbol and it will work within FF

Proceed to download your updates and enjoy FF

Normally my Windows XP downloads updates automatically, but sometimes i check for updates and i use the IE tab add-on in Flock browser