I work at a very large global company (a big pharma), and we're still ninety-some % on XP SP3 for workstations, to the degree that, for one system I support, the vendor came to me with the problem of not having been able to purchase a workstation with anything but Win7 on it, and no longer being able to legally purchase any kind of XP license even to do a downgrade (not sure of all the details, or if this was really an absolute), but needing to get an instance of the system up and running. We ended up having our IT do the XP install with our volume license, on a vendor-supplied, yet-another-third-party-vendor workstation, to support the first vendor's software and interfaced hardware.
It's getting a little contorted out here, and yes, in this case it is because this FDA-regulated company steers like a cow. Technically, we could install Win7, but corporately, we haven't approved a version of our chosen antivirus package yet to run on 7, and so we'd have to either break our corporate guidance and just use Win7's AV, or find another way around the issue. When this particular vendor starts supplying hardware that flat-out won't support an XP install (and this system uses 64-bit), then we'll have a slightly more severe problem.