Do not attempt to boot XP (any version) with a new motherboard, unless you
first do a "repair" installation. There are some very fundamental things
that need to be correct for XP to work with specifc hardware, and a new
motherboard is a lot of new hardware (CPU, RAM, USB, NIC, maybe audio, maybe
video, disk controllers, etc). This is different than Windows 98, in which
you could easily replace almost any hardware and boot into safe mode and
load new drivers.
Note that a "repair" will effectively remove all service packs issued after
the date of the CD. Thus, plan on re-doing a lot of windows updates, unless
you have a recent XP CD. Also, if the CD is pre-SP1, then you may
temporarily lose support for hard drives greater than 127 Gig. An
alternative is to "slipstream" SP-1 or better SP-2 into the retail CD and
make a new CD. Here is a link on how to do that:
http://www.theeldergeek.com/slipstreamed_xpsp2_cd.htm
I have also found that small free program can do slipstreaming for you:
http://www.nliteos.com/nlite.html
Instead of using it to remove components of XP, just use it to combine the
original CD with SP-2.
Slipstreaming can reduce the amount of post-repair XP updating, but it will
not eliminate all of it.
You can do a repair of XP, if you have a retail CD. If you have an OEM CD,
then you are out of luck, since such CDs are intended to be installed only
once on one set of hardware. If the PC is a major brand and came with XP
pre-installed, then you may not even have a CD, but if you did it would not
work on new hardware, since those tend to be BIOS-locked to one motherboard.
If this is a major-brand PC, you might do best to contact their support
group about replacing the motherboard. If they agree to do the work, using
their own motherboard, then they can also make XP function properly and
handle re-activation for you. But, that may not be any cheaper than buying
a new PC, even if they agree to take the job.
Note: If do not already have a retail CD, you can always buy one from any
PC store, but that also is not cheap.
Here are some links about the "repair" process:
http://support.microsoft.com/default.aspx?scid=kb;en-us;315341
http://www.webtree.ca/windowsxp/repair_xp.htm
http://www.extremetech.com/print_article/0,3998,a=23979,00.asp
http://www.geekstogo.com/forum/Repair-Windows-XP-t138.html
After a successful repair, XP should boot normally, but it will certainly
demand that you activate, since changing a motherboard changes a lot of
components that count in the activation scheme. As I recall you will be
given 3 days to do so. First, try activating automatically. With luck, XP
will "phone home", trade some codes with a Microsoft computer and in under
30 seconds your PC will be re-activated. Note that this will only work with
a retail licence and then only if you have not re-activated in the last 120
days (and only if you are lucky). [My own experiences with re-activation
are that the automatic system does not work, because it can not establish a
connection, or similar message.] The manual system requires you talking to
either a human or a computer to trade codes. You need to be able to seee
the PC screen and type, while you are talking. If a computer, speak very
slowly and clearly. You will probably get a human, only if there is some
question about whether you should be allowed to re-activate. If a person
asks what you did recently, just say "replaced motherboard". They already
know what that means in terms of changing many things that contribute to
activation validation. If the human says that you have an OEM version of
XP, see comments above about OEM licenses, and be preapred to by a full copy
of XP.
With respect to activation, XP Pro has the same limitations as XP home.
However, it is also offerred in volume licenses to bussinesses, and their
activation scheme is different than that for the retail version. If you are
talking about a home PC, forget volume licensing, as that is not for you.