I've tried unsuccessfully several times to upgrade my 3G Iphone to 4.0. However I keep getting error codes 3002 & 3194. It seems to be having problems when verifying with Apples servers.

I've found this info on the net but don't really understand it. Can someone explain please and if there's an easy fix?

Error 3002
Update to an older firmware isn’t working, because Apple is no longer handing out SHSHs for the device/firmware combination.
Error 3194
Occurs when trying to install an old firmware and Apple’s server disallows the installation. The only solution is to have SHSH backup and modify the hosts file to point to Saurik’s Cydia server where they are backed up (or localhost if you have it yourself).

Thanks for any help.