Re: How much of a challenge is re-installing XP?
It is aggro from beginning to end.
XP does not install on modern machines with SATA set to AHCI mode. Use the BIOS to alter that setting to COMPATIBLE. When you come to install an AHCI driver (e.g. Lenovo) there may be a procedure where you end up in AHCI mode.
As Bert 1 mentioned, MS Update does not work; but you do a few things first as advised by MS and eventually it gets going.
It can be hard to find device drivers for post-2001 hardware. In my experience Dell and Lenovo have most of what you need for their machines. But third party sites these days just want to stuff you with crapware.
Some hardware seems to have no drivers until you have XP SP2 or SP3 installed.
It will take all evening if you have a good broadband connection.
Windows NT4 used to be as bad near its end. You needed SP3 before you could put in SP6a, then there were updates after that.