How to Know whaich SP (Service Pack) are You Using In Windows XP, and Windows 7

Right-click My Computer and click Properties. In the System Properties Window, under the General tab should show you the version of Windows XP as well as the currently installed Windows Service Pack. In the below example picture, is an example of what this screen may look like under Microsoft Windows XP. As can be seen in the picture, Service Pack 3 is currently installed.

Other Examples

System:
Microsoft Windows 2000
5.00.2195
Service Pack 4

Microsoft Windows XP
Home Edition
Version 2002
Service Pack 1

Alternate method

1. Click Start, Run
2. In the Run line type winver and press enter. Running this command will give you a window similar to the below example, which as can be seen contains the full version information including Service Pack.

Windows XP Windows Version window