newer versions of the "rdesktop" utility have the ability to pass on a smart card to the remote windows machine, using the "-scard" switch.
You'll of course need you reader and smartcard to be accessible/readable by the linux machine you're connecting from. There is a lot of information on the subject on the pcsc (look under software) and the openct project pages.
As for CentOS 5.3 specifics. The coolkey pkcs11 library supports a pretty small subset of smart cards. I believe CentOS 5.3 comes with pcsc, but not openct. As for rdesktop, it comes with a pretty outdated version, I suggest you upgrade.
Good luck, and keep us posted.