Problem with rubygems

Hi guys,

I try to install rubyzip gem as follows(under XP):

C:\Ruby\gem install -r rubyzip
ERROR: While executing gem … (SocketError)
getaddrinfo: no address associated with hostname.

when I try to ping http://gems.rubyforge.org I get these output:
Pinging http://gems.rubyforge.org [205.234.109.18] with 32 bytes of
data:

Reply from 205.234.109.18: bytes=32 time=114ms TTL=40
Reply from 205.234.109.18: bytes=32 time=51ms TTL=40
Reply from 205.234.109.18: bytes=32 time=51ms TTL=40
Reply from 205.234.109.18: bytes=32 time=56ms TTL=40

Ping statistics for 205.234.109.18:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 51ms, Maximum = 114ms, Average = 68ms

How do I fix the socketError?

then I download download the zip file from
http://rubyzip.sourceforge.net/
unzip it,go to the folder containing install.rb,and install it as
follows:

ruby install.rb

By trying the test script I think rubyzip is installed successfully. But
the problem is that I cannot see it in the local gems by typing this
line:
c:\gem list --local

Is there any problem with my installation?

Thank you in advance,

Li

C:\Ruby\download\rubyzip-0.9.1>ping http://gems.rubyforge.org