Also, this http_proxy info must be set on the command line and up2date started from the command-line. Using all current packages as of today. Up2date 4.1.16, kernel 2.4.22-1.2149.nptl.
FYI on using yum or up2date, the proxy_user and proxy_passwd variables and their GUI equivalents do not work trying to get through our proxy. To get through our proxy these values must be set in the proxy address: http://username:password@proxy:port