service pack related

The Service Pack installation routine will normally notify you if any running services or applications will interfere with the installation of the service pack. Since you are required to reboot for the installation to take effect, it's usually a good idea to shut down all running applications (like Exchange and SQL). In fact, if you will be installing the Exchange service pack immediately (or almostimmediately) after installing the Win2K service pack, I suggest the following: prior to installing the Win2K SP, stop the Exchange services and change the service startup type to Manual. This will effectively prevent Exchange from restarting after your reboot for the Win2K SP installation. You can then jump into the Exchange SP installationwithout having to shut down Exchange again. Before you perform the required reboot, change the Service startup type back to Automatic for all Exchange services. Exchange will then automatically restart (hopefully) upon reboot.

If I remember correctly, you must shut down ALL Exchange services to install the Exchange service pack

In addition to Tim Walsh's answer, most (if not all) Windows updates require that the corresponding Windows application is closed prior to updating. If you have not yet done so, I would update the peripheral application patches (especially SQL) *FIRST* before updating CORE installations and service packs. This will give you the opportunity to test the apps before and after Service Pack installation. Core SP's (including W2K SP3) are normally not removable so try and correct problems before theyoccur. Prevention is better than cure. A saying I use, 'Pre-empt and prevent.' should ring true...