There is a command prompt option in Start>Programs>Accessories. Not sure how it acts within XP

Boot to the XP cd. Pressing Delete only gets you into Setup (bios) which you should do if you need to make the cd the first boot device. There is no DOS in XP.

If you boot to XP CD the Recovery Console has some dos like Commands;
--------------------------Microsoft Windows(R) Recovery Console

" The Recovery Console provides system repair and recovery functionality.
Type EXIT to quit the Recovery Console and restart the computer.

1: C:\WINDOWS

Which Windows Installation would you like to log on to
(To cancel, press ENTER)?  (or type 1 & press Enter to use 1: C:\WINDOWS )

(next you get)
Type Administrator password :           (not Use Account (Computer/Administrator) password but default    Administrator  password)
                                                            (usually not set so just press Enter key & if not accepted set Auto Logon to Recovery Console in Registry)
----------------------

Recovery Console Commands , Microsoft info
http://www.microsoft.com/technet/treeview/default.asp?url=/technet/prodtechnol/winxppro/proddocs/recovery_console_cmds.asp

If that doesn't work, or if you need to do more and can't get into Windows, you can try Knoppix.  ( http://www.knoppix.net)  It's a bootable (full) Linux Installation that you can run from the CD without installing anything, but still be able to access files on your HD (although it cannot write to NTFS). 

 ERD Commander 2003 boots dead systems directly from CD into a Windows-like environment. You'll have full access to the dead system's volumes, so you can diagnose and repair problems using tools located on the ERD Commander 2003 Start menu. And you'll have built-in network access to safely move data off of, or on to, the dead system. The Locksmith utility allows you to quickly reset the Administrator password on locked-out systems. With ERD Commander 2003 you can repair a system quickly and easily, saving you time and rescuing your critical data. Boots dead systems directly from CD. Easy, familiar Windows-like interface. Includes the Locksmith utility to reset lost Administrator passwords. Includes FileRestore so that you can quickly find and recover deleted files. Provides access to XP Restore Points on unbootable Windows XP systems. Compares key info on unbootable system with that of a working system for diagnosis and trouble-shooting. Allows for formatting and partitioning of disks Built-in network access to safely copy data to/from dead systems. Repair and diagnostic tools located on Start menu Repair tools include Service and Driver Manager, Locksmith, FileRestore, Registry Editor, Explorer, Disk Management, and Command Prompt. Diagnostic tools include the System Compare, Event Log Viewer, System Information, TCP/IP Configuration, and Logical volumes utilities. Compatible with Windows NT, 2000, XP, and Server 2003.