Very insightful comments here. I have a similar dilemma, as my parents also are on 5.8. It started out as a dual boot with XP, two years ago, in response to five minute bootup times, lock-ups and snail-like performance. By now they have gotten used to VL's speed, stability, and grandchildren-proof design. XP is still available, but not used.
They would be fine with an upgrade, but since they are on another continent, it gets complicated. I set up a different boot profile where a non-standard port is open for ssh. This way I can log in and do updates and changes for them (last time it was setting up a USB printer, they thought that was cool). An OS upgrade would require physical access to the machine.
My brother could re-install XP, but they would soon be back to square one, and I am not convinced it is any safer. Buying a new computer would be expensive, send a perfectly good machine to the junk heap, and involve a steep learning curve.
The perfect solution is not always obvious, or practical.
Flowers and dates are always a good idea!