Quicktime Help Required - Just bought an Ipod but Quicktime isn't working

Hi can anyone help me please? I'm trying to set up itunes but there is something wrong with the Quicktime installed on my laptop. It won't let me update or delete it and I get the following error message when I try to download the newer version from the Apple website 'The installer has encounted an unexpected error installing this package. This may indicate a problem with this package. The error code is 2803.' I then get the message 'The older version of Quicktime cannot be removed. Contact your technical support group'. Any help gratefully accepted!