lozz wrote:iwill have to get a load of blank dvds and copy everything
Nooooooooo, don't use DVDs. 4GB each, and they take ages to burn. No good for backing up a few hundred GB of data.
Get yourself a nice big external USB hard drive (something like a Western Digital MyBook), as much capacity as you can afford (1.5 to 2.0 TB is good). Connect it to the machine, and either use the supplied software, or download CrashPlan, which is a free network-based backup tool. Configure it to back up all the data on your PC, and off it'll trot, copying all the files to its hard drive.
CrashPlan is brilliant - install it on all the networked PCs in your house and tell it to copy it to the PC that has your external backup drive attached. Configure CrashPlan on that PC to backup these other PCs' data to the drive, and it will just sit in the background and ensure all your files are backed up (incremental backups too, so it'll only backup what's changed since the last backup ran). And it's free too, which is even better.