Without these critical updates, you have some important security issues, which need to be fixed as soon as possible.
You can directly install the latest service pack, there is no need to install the previous service pack's!
If all updates are installed (or if you have troubles with the Windows Update website), you can safely delete the files in the following folders: C:\Windows\System32\Catroot2 C:\WINDOWS\Software Distribution\Download I can't imagine you would like to roll back the installed high priority Windows updates, especially if there are no problems.
By the way, Windows XP is since SP2 provided with and auto update function for critical updates (the yellow shield in the system tray) and the Security Center (the red shield in the system tray).
On the page how to optimize the Windows services, you can read how to disable the Security Center.
WD hard drives use drivers that are built into the operating system (OS).
It is extremely rare for the built-in drivers to become damaged or corrupted.Problems with Windows Update are quite common: already installed updates keep coming back after a restart or Windows Update shows an error message and refuses to go on.Many of these problems can be solved easily by resetting Windows Update!The next step is to delete the (content of) folder C:\Windows\Software Distribution (which contain the update history and downloaded updates) using the Windows Explorer.Although it is not necessary, this folder can be used as back-up by simply renaming it to Software Distribution (in stead of deleting the folder).These updates can be massive, especially if service pack 3 is not installed yet.