Desktop annotation utility?

[BJG]

Most of our whiteboards are Smart, but we also have a handful of old Promethean ones. I recently upgraded the PCs running these to ActivInspire because the old version of ActivStudio wasn't Windows 7 compatible, and only just realised we're not eligible to a free upgrade to the Pro version. Unfortunately the free Personal version lacks desktop annotation, so I was wondering if there were any other options/workarounds...? (Not sure how much upgrading our ActivStudio Pro 2 boards to ActivInspire will be, but I doubt it'll be cheap.)