Free 64-bit computing
Windows XP is available in 64-bit as of today. The interesting thing of it is that you can upgrade to it free if you are already running the 32-bit version on a 64-bit processor. The downside is that the number of drivers available is limited. I'm a little surprise that Microsoft made the upgrade free, but I guess it does help drive adoption of the 64-bit platform a bit and they probably wouldn't have been able to charge much anyway.