For those of you that can, you can still get XP Home or Professional for cheap. Here's how:
Army Knowledge Online (AKO) is slowly migrating to become Defense Knowledge Online (DKO) at
http://www.us.army.mil/. The good thing about this is that if you're AD, Reserve, Guard, Civilian and/or Retired (regardless of service), you can sign up for an account. Yeah, you'll need your name and SSN to verify who you are, but once you get the OK, you'll be in. This is important.
There's a tab on the main navbar at the top of the portal that says Self Service. Click on that to get a pull-down menu, and click on Army e-Commerce. That will bring up the Fort Monmouth Army e-Mart, or what is now called Computer Hardware, Enterprise Software and Solutions (CHESS,
https://ascp.monmouth.army.mil/scp/index.jsp). From there, click on "Government Employee Purchase Program" on the right side of the screen (it'll be the top link in the blue "More CHESS Resources" box).
This link brings up the entire list of hardware and software providers that have contracts with the USA. Microsoft is at the bottom of this list. Now, here's the reason why I said having an AKO/DKO account is important. To get to the MS EPP site, you will need to have an @us.army.mil address. They won't let you in without it. That and the provided code will get you in to the MS site, where copies of XP Home run at $64 (+tax and shipping) and XP Pro run $129 (+tax and shipping). These are FULL versions. Trust me, it's worth it.
Funny how a DoN Civilian in the Excepted Service can use the Army for cheap stuff. Too bad Apple doesn't give you a decent discount.