Gary has an old laptop that constantly reboots when he turns it on. Leo says that it might not be a hardware problem. A simple reinstall of Windows should fix it. He should just get his old Windows discs out and boot to the CD.
If nothing comes up and it just reboots before it even gets to the Windows screen, it could be a BIOS issue. The bios battery may be dead and as such, the laptop has no reference for settings. It also may be just plain worn out. The power supply could be dying. He could try booting into the laptop without the battery, and just have it connected to AC power.
It's probably better to just buy a new computer. It's not worth fixing because for a bit more money, he could just get a new PC that's faster.