http://www.talkandroid.com/guides/how-to-take-screenshots-on-your-nexus-one/
summary
- install java sdk
- install android sdk to C:\ProgFiles\android-sdk-windows
- run C:\ProgFiles\android-sdk-windows\sdk manager.exe
- choose usb drivers
- goto App settings | Development | enable USB debugging
- plug in android usb cable
- install android usb driver from C:\ProgFiles\android-sdk-windows\usb_driver
- run C:\ProgFiles\android-sdk-windows\tools\ddms.bat
- wait 15 seconds
- press CTRL-S (on your PC)
- save screendump