You may have a partition on the HDD that has your XP on there. I have had it on my Dell and Toshiba. Anyhow, when I replace my motherboards I usually end up having to install the drivers for that particular motherboard since they will be different and windows will tell you that it has found new hardware. So make sure you have a disk with all the drivers for your new motherboard and follow the install instructions. At this point you really have no other option than to give it a go or purchase a new copy of xp as well as having a disk with all the drivers for your Acer. I hope this makes sense and it is really not all that bad and complicated. Good luck and let us know.