XP (notice no SP1 or SP2) can't recognise such large drives. This is discussed at http://www.48bitlba.com
Once you install the machines drivers and SP2 then it should work.
As to backup of this OS, your plan has some kinks to be worked out.
Bob
I purchased a new Seagate 300GB external hard drive (USB 2.0). I am attempting to connect it to a HP laptop running Windows XP with all of the updates available until mid-June (when all of my network connections disappeared after a hung-up installation of XP updates). I bought the hard drive so that I could back everything up and reinstall XP.
Upon connecting the drive to my laptop, the new hardware is recognized...but there is a problem with the drivers (not Windows-certified).
I connected the hard drive to our desktop computer, which recognized it and installed it immediately...no problems. I checked the drivers that were associated with it (disk.sys and partmgr.sys). Those were already on my laptop, but I copied them from the desktop computer to the laptop just in case they were corrupted. I am still receiving the driver errors on the laptop. I cannot connect to the Internet from the laptop, because of the missing network connections. I have run out of ideas, and would greatly appreciate any help!!

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