Missing System.Web.UI Namspace in my Visual C# Express Edition

Hi,

I just downloaded Visual C# Express Edition and when im trying to build my class library Im getting this error:

The type or namespace name 'UI' does not exist in the namespace 'System.Web' (are you missing an assembly reference?) 

and I could't find System.Web.UI namespace in .net componets under the Add Reference...

Any Ideas...

TIA.

Maher
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