How to boot from new hard disk?

Hai,
This setting controls the order that the BIOS uses to look for a boot device from which to load the operating system during the DOS boot process. Older machines do not have this setting; they look at the floppy drive first (A:) and then the hard drive (C:). Most systems will at least let you choose between "A:, C:" (the default) and "C:, A:". Newer systems will allow you to boot from the CD-ROM as well; in this case there will be six different combinations listed. The default will normally be "A:, C:, CD-ROM".

Booting off the second floppy disk, B:, has not been an option on any PC I've ever seen.

Some BIOSes are getting even more advanced in terms of the boot sequence options they will allow. Some systems will now allow you to boot off a different IDE hard disk than the primary master (C:), or let you boot from a SCSI device instead of IDE even when both are used in the same system (normally the IDE device gets preference).

Changing the boot sequence to seek from the hard disk drive first instead of the floppy disk drive has some advantages, and also some disadvantages. There are two main advantages. First, if the floppy disk isn't bootable, you virtually eliminate the chance of a boot sector virus spreading to your hard disk from a floppy. Second, you have a measure of security and reliability since when the floppy disk is bootable, anyone can write their own system files and boot the PC with their floppy, bypassing the standard startup files on the hard disk.

can your xp install 'see' the new hard drive?
if so you need to modify your xp boot.ini to add the nt server os to the boot menu. try using recovery console with bootcfg /rebuild command to add the entry.