Today our local IT Support shop has fitted a new hard disk in the laptop. I've set it to boot from the multidrive (via F10). When I insert any CD, including XP Pro it reports non system disk or disk error - replace and strike any key. What am I doing wrong?

You either have to set the bios to boot the cd first then the hard drive or you are not seeing the hit any key to boot cd or similiar message. You may also have an option during boot that by hitting a function key like f12 you will be presented with a boot menu. Choose the cd. I am curious as to why your tech support isn't taking care of this for you? They should be installing anti bad guy stuff and configuring it for you also.