There is a way but it is high risk it won't work.
-Image the HD in the old system.
-Boot with just the image HD installed.
-Use Ccleaner.exe to uninstall the software drivers for the hardware (vid, sound etc.) and set the video to 800x600.
-Uninstall all of your hardware devices in Device Manager, including MB chipset functions.
-Move the HD to the new system and it's copy of windows will see all new hardware and start a new HW found effort.
If you get lucky you will have found and removed all vestiages of the old drivers and you will get a clean setup of Windows on the new machine with all your programs and data intact. Sometimes this goes well sometimes, not.
If you are going to a system with an identical or similar MB chipset then chances of success are high.
Note - as mentioned above Windows will cry rape and force a voice activation. Just tell them you have upgrdade the MB, CPU and RAM and they will ask if the new system is the only system using this copy of windows. The correct answer is obvious. ;-)
You can then do a windows key replacement on the old machine at your leisure since both will be activated.
http://downloads-zdnet.com.com/Wind...ewer-XP-Key-Changer/3000-2094_2-10349010.html
Plan B is similar but when the new HW found fails or if the new system performance is sluggish you do a repair install of windows on the new system.
Then do a complete defrag of the HD. You will loose your program usage since the registry will be wiped but you can install over the old ones and most data and configurations will be intact.
Plan C - if A and B don't work out or sound like too much trouble, reformat and do a clean windows install on new system. Then use the windows files and settings transfer function to copy all data and setup information from the old machine to the new machine across a LAN connection.