I ran:
yum update --enablerepo=stephd1,virtualbox,dag
db yum_repositories show:
addons=repository
EnableGroups=no
GPGCheck=yes
MirrorList=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=addons
Name=CentOS - addons
Visible=no
status=disabled
base=repository
EnableGroups=no
Exclude=initscripts,libgsf
GPGCheck=yes
MirrorList=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os
Name=CentOS - os
Visible=yes
status=enabled
centosplus=repository
EnableGroups=no
GPGCheck=yes
MirrorList=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus
Name=CentOS - centosplus
Visible=no
status=disabled
contrib=repository
EnableGroups=no
GPGCheck=yes
MirrorList=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=contrib
Name=CentOS - contrib
Visible=no
status=disabled
dag=repository
BaseURL=http://apt.sw.be/redhat/el4/en/$basearch/dag
EnableGroups=no
Exclude=freetype,htop,iptraf,rsync,syslinux
GPGCheck=yes
GPGKey=http://dag.wieers.com/packages/RPM-GPG-KEY.dag.txt
Name=Dag - EL4
Visible=no
status=disabled
epel=repository
BaseUrl=http://download.fedoraproject.org/pub/epel/5/$basearch
EnableGroups=no
GPGCheck=yes
GPGKey=http://dl.fedoraproject.org/pub/epel/RPM-GPG-KEY-EPEL
MirrorList=http://mirrors.fedoraproject.org/mirrorlist?repo=epel-5&arch=$basearch
Name=Epel - EL5
Visible=no
status=disabled
extras=repository
EnableGroups=no
GPGCheck=yes
MirrorList=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras
Name=CentOS - extras
Visible=no
status=disabled
fws=repository
BaseURL=http://repo.firewall-services.com/centos/$releasever
EnableGroups=no
GPGCheck=yes
GPGKey=http://repo.firewall-services.com/RPM-GPG-KEY
Name=Firewall Services
Visible=yes
status=disabled
smeaddons=repository
EnableGroups=yes
GPGCheck=yes
MirrorList=http://mirrorlist.contribs.org/mirrorlist/smeaddons-8
Name=SME Server - addons
Visible=yes
status=enabled
smecontribs=repository
EnableGroups=yes
GPGCheck=yes
MirrorList=http://mirrorlist.contribs.org/mirrorlist/smecontribs-8
Name=SME Server - contribs
Visible=no
status=disabled
smedev=repository
EnableGroups=yes
GPGCheck=yes
MirrorList=http://mirrorlist.contribs.org/mirrorlist/smedev-8
Name=SME Server - dev
Visible=no
status=disabled
smeextras=repository
EnableGroups=yes
GPGCheck=yes
MirrorList=http://mirrorlist.contribs.org/mirrorlist/smeextras-8
Name=SME Server - extras
Visible=yes
status=enabled
smeos=repository
EnableGroups=yes
GPGCheck=yes
MirrorList=http://mirrorlist.contribs.org/mirrorlist/smeos-8
Name=SME Server - os
Visible=yes
status=enabled
smetest=repository
EnableGroups=yes
GPGCheck=yes
MirrorList=http://mirrorlist.contribs.org/mirrorlist/smetest-8
Name=SME Server - test
Visible=no
status=disabled
smeupdates=repository
EnableGroups=yes
GPGCheck=yes
MirrorList=http://mirrorlist.contribs.org/mirrorlist/smeupdates-8
Name=SME Server - updates
Visible=yes
status=enabled
smeupdates-testing=repository
EnableGroups=yes
GPGCheck=yes
MirrorList=http://mirrorlist.contribs.org/mirrorlist/smeupdates-testing-8
Name=SME Server - updates testing
Visible=yes
status=disabled
stephdl=repository
BaseURL=http://mirror.de-labrusse.fr/smeserver/$releasever
EnableGroups=no
GPGCheck=yes
GPGKey=http://mirror.de-labrusse.fr/RPM-GPG-KEY
Name=Mirror de Labrusse
Visible=yes
status=disabled
updates=repository
EnableGroups=no
Exclude=initscripts,libgsf
GPGCheck=yes
MirrorList=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates
Name=CentOS - updates
Visible=yes
status=enabled
virtualbox=repository
BaseURL=http://download.virtualbox.org/virtualbox/rpm/rhel/$releasever/$basearch
EnableGroups=no
GPGCheck=yes
GPGKey=http://download.virtualbox.org/virtualbox/debian/oracle_vbox.asc
Name=RHEL/CentOS-$releasever / $basearch - VirtualBox
Visible=no
status=disabled