Perhaps the installed OS isn't supported any more and the repositories are not available?
You would be wise to reinstall a newer linux distro, based on security concerns. If you want a free full blown gateway, then have alook at Clarkconnect:
http://www.clarkconnect.com/ it's free, but your hardware may not run. check the minimum requirements.
Or if it's
just an internet gateway and nothing else, something like IPcop or smoothwall. These will run on allmost anything. I use IPcop myself.
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