Can i have two sata hard drives each with an os on one computer?
It probably won’t work like you want it to, Computer B has different hardware than Computer A, and the XP install on A will recognize that and probably won’t boot up (Microsoft does this on purpose, so you can’t just move/copy an install to another computer). But if you just install the hard drive from A into computer B, you will be able to see the files on hard drive A as another drive when you boot B (it should show up as E: or F: or some higher letter) and you can access the files on it. This shouldn’t damage the XP install on hard drive A, so you could put it back into computer A and it should still work fine. Otherwise, you can install hard drive A into computer B, and do a fresh XP install on hard drive A, then you would be able to boot to either drive (XP will automatically set up the boot loader, which gives you the choice), but this would lose the data and documents you now have on hard drive A.