Before you install SharePoint Services V3 You must install and configure IIS, .NET Framework v2 and Windows Workflow Foundation (short info about Windows Workflow Foundation and How to install the Microsoft .NET Framework version 3.0)

Step 1.
Download Windows SharePoint Services 3.0 from the Microsoft Download Site and Run

Step 2.
the files are extracted, and then setup runs, read the license agreement, select the I ACCEPT the terms of this agreement check box, and then click Continue.

Step 3.
on the “Choose the installation you want” page click Basic.

Step 4.
Setup runs and Yo can see Installation Progress.

Step 5.
The installation is complete.