Gem update --system returns error

Hi guys,

First off, I am completely new to programming and hence obviously also
to both Ruby and RoR. Please do bare with me. Yoroshiku onegaishimasu!

I am having trouble understanding what to do when the following error
appears when I try to update RubyGems:

C:\InstantRails\rails_apps\gem update – system
Updating RubyGems…
ERROR: While executing gem … (Gem::RemoteSourceException)
HTTP Response 302 fetching RubyGems.org | your community gem host

I am using instructions as composed by Patrick Lenz in Simply Rails 2.
I’m on Windows Vista SP1.

Thanks in advance!

Alex