This link is essentially just a notice that the update has been releassd, and lists the files contained in the patch download. It includes links to where Microsoft claims to provide free support for anyone having problems with the patch.
Since this patch does affect DNS, it's the most likely to have caused problems with your internet hookup.
There is no obvious reason why the KB951978 patch should affect broadband connection, but anything is possible.
The KB951748 patch quite probably relates to a recently (two weeks ago) reported MAJOR PROBLEM with DNS servers that could allow "address spoofing" on large numbers of internet servers to redirect users to fake servers where malware exposure would be the intended result.
News articles have praised the "rapid response of worldwide service providers" in "fixing" this problem to prevent the "total destruction of the internet." "Rapid response" is frequently the euphemism applied to "released with less than normal testing."
The published stories state that "no exploits using the vulnerability have occurred," but the site responsible for registering and issuing Domain Names was reported as having been "hacked," quite possibly using this vulnerability, less than a week ago. The result was that people attempting to connect to the Name Service site were redirected to a phony site. The affected service asserts that no malware was found at the phony sites, and that the problem was corrected "in less than 20 minutes," but affirms that it did happen. It would appear to have been a "demonstration of concept" attack.
Microsoft does not confirm that this is the purpose of the patch; but IF THIS IS THE VULNERABILITY that the KB951748 patch is intended to fix, then it IS A BIG DEAL; but the main effort applies to Servers. The patch may be required for individual user machines to adapt to the server changes as more servers are updated.
Also note that this vulnerability is not just for Windows, but affects ALL servers using DNS regardless of operating systems used. The vulnerability appears to be in the port access permissions that are part of the DNS specification, although details won't be released until "the web" thinks the problem has been fixed.
OTHER ISSUE:
It may also be noted that a Press Release – undated but circulated within the past week – announced (again) that (one more time) Microsoft will begin (once more) to download WinXP SP3 via Automatic Updates. The announced start (this time) for the Automatic Download and Installation of SP3 was to begin TODAY (10 July 2008) starting with users in Australia.
SP3 has been available for download at the Microsoft update sites, but has been optional. If it's been moved to "Automatic" it may be assumed that it will be automatically installed for anyone receiving auto updates.
No estimate was given in the PR for how long it will take to download to all users, but Automatic Updates claim to serve all users in the US at least once per week.