Need Directions

My old Dell E550 that came with xp and I upgraded it to Win 7, and things were good till the mobo died. Received an identical E550 from a friend for nothing, but it came to me as is. I installed Mcafee total protection as I have the 5 system cover deal with them. I like to maintain two systems, one current and one the prior, the other is Win 10. Removed many of the unwanted program that were on the xp using Iobit uninstaller, but as soon as I tired to access IE I ended up with firewall problems, and cannot do any Windows updates either. Can get to the internet with Mozilla Firefox but not IE. Seen many suggestions on the net to solve the problems I am having do to the prior owner profile being on this machine along with other issues in documents and files. Also I don't have the experience to fix the fire wall, and some of the other issues, regardless of my internet hunting for fixes. My goal is to have xp 3 working (as that is how the machine came) even if I have to purchase an new install disk so that I can then use my upgrade to install Win 7 and have the two different systems again.
Looking for suggestions as to the least complicated way of getting xp running on this machine.

 

least complicated is to reinstall xp. you can look at the partitions and see if there is a hidden partition that has xp out of the box from dell, this will be there if the drive has not been wiped. but to get to xpsp3 is another thing, first if the partition is there reinstall xp and find out what service pack you do have then we can update from that point but you do not want to go online until you have installed up to service pack 3 and ie8 so that you will be able to go to microsoft updates website.