normal household surfing... do we need it?

any idea what it does in your computer? Im thinking of removing it.

Where do I find window disk management utility? Cant find it on my desktop but laptop has it.

If you're using an ATi card, the .NET Framework displays the GUI for the Catalyst Control Center. FYI, Sony Sound Forge also uses the .NET Framework. There are a few versions, namely 1.1,2.0 and 3.0. You can install all 3 of them with little or no issues.
For more info, read this article.
http://en.wikipedia.org/wiki/.NET_Framework

Hope that helps.

Heard it's a strong and powerful platform introduced by Microsoft.

You most probably don't need it, but it's installed because some app you installed does. So if you uninstall it, expect something to break.

just install version 3.5 sp1 its a big download but has everything you need plus updates.

.NET Framework is a runtime system for applications developed using Microsoft .NET platform. If you're just normal PC user, the probability of not using it is high so you can uninstall it. But some software do need .NET Framework to run on your PC, such as Paint.NET, Sound Forge, Vegas etc.