If you have windows xp,sp2 or windows 2003,you can follow these instructions to install .NET 3.0 (all downloads are free, so you can install it)

STEP1:

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You can install Visual c# express edition from here (Its free, so you can download from here)

http://msdn.microsoft.com/vstudio/express/visualcsharp/download/

STEp2:

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Please use following instructions to install .NET 3.0

(a)

Install .NET 3.0 runtime

http://www.microsoft.com/downloads/details.aspx?FamilyId=10CC340B-F857-4A14-83F5-25634C3BF043&displaylang=en

(b)

install windows SDK

http://www.microsoft.com/downloads/details.aspx?FamilyId=C2B1E300-F358-4523-B479-F53D234CDCCF&displaylang=en

(c)

Install Visual studio extensions

http://www.microsoft.com/downloads/details.aspx?FamilyId=F54F5537-CC86-4BF5-AE44-F5A1E805680D&displaylang=en

 

After this, you can write WCF applications in vC# express edition