Minimum System Requirements for installing Silverlight plug-in is as follows:


PC TypeProcessorRAMOperating System
Windows PC 500 MHz or higher, x86 or x64 bit processor128 MBWindows XP SP2+
Mac Power PC PowerPC G4 800 MHz or higher128 MBMac 10.4.8 or higher
Mac Intel-basedIntel Core Duo 1.83 GHz or higher 128 MBMac 10.4.8 or higher

Minimum System Requirements for installing Silverlight SDK for development is as follows:


Operating System- Microsoft Windows XP Service Pack 2 or higher
Developer Tools - Visual Studio 2008 SP1 (for Silverlight 3) 
- Visual Studio 2010 (for Silverlight 3 & Silverlight 4)
Designers Tools- Microsoft Expression Blend 3 (for Silverlight 3) 
- Microsoft Expression Blend 4 (for Silverlight 3 & Silverlight 4)
Silverlight SDK- Silverlight 3 Tools for Visual Studio 2008 SP1 
- Silverlight 4 Tools for Visual Studio 2010