|"? if I put this in my other pc and re format it can I install the os and then put it back in the other pc will it run then ??'|
It will only run if the other pc is identical.
What you can do is uncable the good (already has an operating system ) hard drive.
Cable up the drive ( no need to bolt it in, just let it sit loose ) to install XP & run the XP install to the point of deleting all the partitions, formatting to NTFS & then cancel the install.
Now put the drive back where you want it & see if you can finish the install.