is this update really necessary?

[Rann_03]

Express install allows you to quickly download and install only the critical and security updates your computer needs.


Microsoft strongly recommends that you install the following high priority updates to help keep your computer up-to-date and secure. To install these updates, click Install.


Total updates selected: 1 items, 10.2 MB, 2 minutes Install...
High Priority Updates
Microsoft Corporation - Windows XP family

Microsoft .NET Framework 1.1 Service Pack 1
Download size: 10.2 MB, 2 minutes
Microsoft .NET Framework 1.1 Service Pack 1 resolves various issues found after the initial release of .NET Framework 1.1. These include both security- and non-security-related issues. After you install this item, you may have to restart your computer. Once you have installed this item, it cannot be removed. Details...

what does this thing do ?

[Play_The_0dds]

if you dont know then you probably dont use net framework. if you have a web site, do on-line school/college, do any programming you may want to keep it. if none of those apply, go to add remove programs and remove net framework, it is a optional add on, the security update is needed if you keep the service.

http://msdn.microsoft.com/netframework/

the link is to microsoft's site and you can look around and see what all it does and if you want it.

[Xanex]

For the average user this isn't a requirement, it will load a few more services onto your machine that you do not need.

ignore it untill you need it