Installing Security Certifcates for all users on a Windows XP machine

Question

Hi,

I am required to install two security certifcates on user's PC's to allow them to connect to a certain Australian Government website to perform searchs.

I can perform this manually (via Certifcate Import Wizard) when the user has logged into the machine, however when a different user logs in, the certifcates need to be re-installed for that user as well.

Q1. Can certifcates ( the file extension is .p12) be installed in such a way that any user using the PC can use the certifcates?

Q2. Can the installation of the certifcates be automated ( via SMS? ) to install both certifcates and enter the requried password?

Thanks,