Hello Peter
If you are using Win98SE then this is a reasonably stable system, providing you do not overload it with to many programs, however a word of warning, due to the way the hard drive has to be formatted for 98 to work, security is virtually none existent compared to 2000/XP, so don’t leave any critical information on there, just in case (Hopefully it will never happen) your Laptop gets stolen.
Regarding Backup then always use an External USB/Firewire Drive, that way you can unplug it before doing anything serious (Reinstallation etc) on your computer. (It can also be used to Backup your Laptop)

Bill