The symptoms are that the screen goes black (not sure whether it is backlight) but suspect not as the machine doesn't sleep when the lid is closed, which you would expect it to if it were the screen. If you power it off then about two times in three it will not reboot properly and the fan stays on... sounds like something temperature or sensor related to me. It's probably not worth trying to get it fixed as it's well out of warranty.
Anyway, I think I need to start thinking about what will replace it. Do I get another Mac? I'm inclined not to as I can't get the VPN client for it anymore as Checkpoint don't make them freely available and work will only provide Windows ones. I should have the old version available somewhere, but there's always the risk that it'll stop working and I won't get an updated one.
Normally I'd start thinking about Linux machines at this point, but it looks like connecting to the VPN at work will be equally if not more difficult on the Linux box. This rather leaves a Windows machine. Ick. Or, possibly, Windows running in a VM on a Linux box.