Windows CE 5.0 Device Emulator
http://www.microsoft.com/downloads/details.aspx?FamilyID=a120e012-ca31-4be9-a3bf-b9bf4f64ce72&DisplayLang=en
(This requires XP SP1, or Windows 2000 SP4)

Windows CE .NET
http://www.microsoft.com/downloads/details.aspx?familyid=77c223ab-b01f-4173-bebf-b0d24d0f0606&displaylang=en

Emulator Images for Windows Mobile 2003-based Pocket PC Development
http://www.microsoft.com/downloads/details.aspx?FamilyID=57265402-47a8-4ce4-9aa7-5fe85b95de72&displaylang=en

Microsoft Pocket PC 2003 SDK
http://www.microsoft.com/downloads/details.aspx?familyid=9996B314-0364-4623-9EDE-0B5FBB133652&displaylang=en

Microsoft Pocket PC 2002 SDK
http://www.microsoft.com/downloads/details.aspx?FamilyID=2dbee84a-bd94-4167-b817-2b2e548b2e92&displaylang=en