I got a question today about developping to CRM 2011 from a XP workstation,
A quick look to the SDK (http://msdn.microsoft.com/en-us/library/gg328350.aspx) lists XP as un unsupported platform for the 2011 endpoint and (more interesting) the reason why
"The following is a list of the types of actions that are not supported:
Development using the Microsoft Dynamics CRM 2011 assemblies (specifically, Microsoft.Xrm.Sdk.dll) is not supported on Windows XP due to a dependency on Microsoft.IdentityModel.dll. However, you can use the Web Services (WSDL) from XP. For more information, see Use the WSDL Endpoint."
Microsoft.IdentityModel.dll is part of the windows identity foundation which not supported/installable on XP, the list of supported OS is as follows :Windows 7;Windows Server 2003 Service Pack 2;Windows Server 2008 R2;Windows Server 2008 Service Pack 2;Windows Vista
I played a bit with the idea of using the ORCA tools to force the install to XP, but here's an easier way to make it work on XP (in an unsupported manner)
- Find a machine running one of the supported OS above, download and install WIF if not yet present (http://www.microsoft.com/downloads/en/details.aspx?FamilyID=eb9c345f-e830-40b8-a5fe-ae7a864c4d76) and then the WIF SDK (http://www.microsoft.com/downloads/en/details.aspx?familyid=C148B2DF-C7AF-46BB-9162-2C9422208504)
- Copy C:\Program Files\Reference Assemblies\Microsoft\Windows Identity Foundation\v3.5\Microsoft.IdentityModel.dll to the XP Machine
- On the XP Machine (with VS2010), register the dll into the GAC C:\Program Files\Microsoft SDKs\Windows\v6.0A\bin\gacutil.exe /i Microsoft.IdentityModel.dll)
Note that this just a temporary workaround, if you develop against the CRM 2011 endpoint, I would strongly suggest using a more modern platform like a Windows7x64.