How difficult could it be to get update from Eclipse? Wait until you sit behind corporate proxy!
If it is a NTLM proxy and Eclipse 3.5, stop trying! it WILL NOT work. You not only find solutions here, but also find testimonials of how many time has been wasted on this topic
http://demeringo.ovh.org/blog/?p=103
For me, add a CNTLM is the best
