Problem with Dell 8200

I know this thread is a bit long in the tooth but I have some suggestions to make, hopefully helpful ones. This post doesn't really concern Windows XP, though, and others seem to have the software inquiries covered well.

Firstly, you (Mark Twain) mentioned that the top fan (power supply fan) wasn't spinning properly. That means that the sleeve bearing in that fan is probably completely dry with no lubricant left. You could either replace the power supply with a new one (provided that it doesn't have a rocker switch, has the proper connectors, has an 80mm exhaust fan, etc) or disconnect the PSU from the motherboard, open it up, unscrew the fan, peel the sticker off, pop off the rubber cap, and oil it with something like sewing machine oil (that should do the trick). Since this PSU has a fan header instead of soldering the PSU fan straight to the PCB, you could also replace the fan with another 80mm one (provided that its connectors are long enough and of the right size) without having to get out a soldering iron.

From what I can garner of the images, the PSU is probably a NPS-250GB and probably has an ADDA sleeve bearing fan (AD0812HS-A70GL), but some of them do come with Sunon sleeve bearing fans (those, however, make noticeable noise, while the ADDA fans are very quiet). Those ADDAs are known to seize prematurely because ADDA don't impregnate them with enough lubricant from the factory. It could also be a Sunon fan (KD1208PTS1H) which could also be failing because the bearing is dry. And it is perfectly possible that the PSU is failing and wreaking havoc upon the system. Those older Newton Power units, of that age, tended to use mediocre to bad capacitors made by a Taiwanese company called Luminous Town Electric (a company associated with the aforementioned "capacitor plague"). Most of those capacitors are probably LTEC, anyway, but the two big capacitors on the input are likely made by Nichicon so you can leave those alone.

And while this particular power supply is designed well enough to offload stress from those less than stellar capacitors, with a seized PSU fan that unit will get hot enough to kill the capacitors (if the PSU fan is spinning, without any lubricant it certainly isn't spinning fast enough to properly cool the unit... and even if it is spinning, there's no telling when it will stop spinning during operation due to a lack of oil).

From what I can tell, the CPU fan is a JMC/Datech 9232-12HBTL-2. Those are also notorious for going bad but since you oiled it it may be fine. The only other thing of concern is those yellow polymer capacitors (Fujitsu polymers) on the output of the CPU VCORE. Those earlier polymers (those made by Fujitsu, not Nichicon or Sanyo) were occasionally known to fail because they weren't sealed well enough from the factory but if yours aren't bulged and the system isn't misbehaving it's probably safe to leave those be too.

On the other hand, this is a lot of work to be doing for such an old computer. So my comments above are again only suggestions.