sbs2011 server Ssl certificates

we have a single Microsoft sbs2011 server on which I have added a RapidSSL certificate for remote.domainname.co.uk

this seems to working fine.

however, when I look at the server certificates on the IIS manager, I notice that 3 of the listed certificates have expired. I did not add these and I font even know if we need to do anything, but thought I should ask.

we have certificates that have expired as follows :/

issued to - Sites
issued by - domain-sbs2008-ca
expired - 26/8/2013

issued to - remote.www.domainname.co.uk
issued by - domain-sbs2008-ca
expired - 26/8/2012

issued to - domain.domainname.co.uk
issued by - domain-sbs2008-ca
expired - 26/8/2012

it may well be that we don't need these, is they do not seem to be causing us any problems other than the warning in the server event log.

the question is do we need to renew these, go we just leave them, or should I remove them?

any advice would be appreciated.

many thanks