How to download iphone update to desktop?

I'm trying to restore an iphone and before I can it tells me I have to update it, so the download begins which is taking about an hour and so far into the download my phone gets kicked out of itunes which means I have to reconnect and start the download again is there anyway I can download the latest update straight to my desktop? Or restore an iphone without having to upadate first?

Strictly iphone updates won't run on your desktop, their designed specifically for the iphone. But, if you mean something else. Restore the iphone, charge it up, and try it again.