can nsis tell whether its XP or XPE

How can I write a NSI script for my application to be able to tell whether its XP or XPE. Say for example: I wanted to include netsh firewall add program on my script but I believe WIndows 2000 does not support this. Or Just be able to tell what OS its installing?
Greatly appreciate any help.

THanks

Hi.
See "Nsis user manual\Appendix C: Useful Scripts\Get Windows version"...