Hi,
It is not supported installing Backup exec for windows software on Windows 2003 64 bit Intel P4 Dual Core Processor Server.
Refer: http://support.veritas.com/docs/278254
Whereas you can install Remote agent on 64 bit Server.
Refer: http://seer.support.veritas.com/docs/280701.htm
http://seer.support.veritas.com/docs/275657
Thanks!