Specifying boot volume

I recently added a fast hard drive to my system using an ATA pci card and copied the contents of my C drive to it. I want to boot from that volume to gain the speed advantage. All Win tech support docs I have seen assume different systems are installed in a multiple system configuration and you specify the system you want to boot. My system now has WinXP on two different volumes and I want to secify the the fast boot volume. How is that done?