First, most machines built after 2001, running XPSP1 or later, should have no real problem with large drives, though some might require a BIOS update -mind you now, thats "
SHOULD have no real problem]", not "WILL have no real problem[/i]" ... a trip to the support pages of the machine vendor's website can be a good idea - you may find what you want to know. That said,
HERE'S a decent, if slightly dated, discussion of the ins and outs of upgrading to large drives - most of it is still perfectly applicable today.
Second, an AMD K5 380/128RAM will prolly run XP, but prolly won't be able to do much with it in any fashion likely to satisfy you.