Increasing hard drive size

I have read a lot of threads about upgrading hard drives in a Sky+ (not HD) box. Most, if not all, involve the Copy+ software route. As I have no wish to save any data on the old disk. All I want to do is increase the storage capacity. Can I, just put in a new disk, unformatted, and will the box do all formatting etc for me?

Also is there a limit to the disk size I can fit without going down the Copy+ route? If so what is it?

FYI I have a Pace TDS470N with a 80GB drive.

Thanks in advance for your help.