IMAC expert

We have an IMAC that makes a fan whirring noise all the time. I took it in to Apple and they advised there is a program running in the background that needs removing (they could not find what it was). I need to copy all of my photos, videos, documents etc on to a hardrive and whilst I could probably do this myself eventually, I do not have the time. Once all documents are safley backed up then Apple advised me to upgrade to Snow Leopard. The IMAC also has emails that need to be backed up and then reinstated on the IMAC. I could have more IT related work if this project is carried out successfully.