I'm happy to find this thread, because I bought a couple of Dell Dimension XPS D233s just for the Palo Alto case (I really like the way they build) and the power supply because I had a couple of MicroATX boards with no home. My daughter had exactly the same case with a PIII 450 system from CompUSA that had an SE440BXII board that had both Intel and ATX standard connectors and it was a sweet upgrader. I never suspected the ATX power supply would be non-standard.
The problem I was trying to overcome was the modular plug/ribbon cable combo from the front panel itself to the motherboard connector. The modular plug has the same dimension and pin spacing as an IDE cable but has 16 pins with #14 blocked. I was hoping someone else had come up with a handy little male end that was pinned out for standard ATX with the separate connectors for DC Power, Reset, Pled, HDled and Speaker, but have not located anything yet. I was about to start stripping the ATX front panel connectors out of a dead case and stuffing them into the modular plug and siliconing the whole shebang to isolate them. Good thing I didn't get too far along.
OK, so you can replace the power supply--I figured the 200W units would be ok, darn it--and the old motherboard, but what do you do about the modular plug? I didn't want to strip the case down that far, but come to think of it, there must be a little piece of pcb in the front panel that has a matched set of pins to the motherboard for the plug on the other end of the ribbon cable, maybe it would be easier to attack it from there.
Does anyone know if there are ATX front panel wiring extenders? Kinda like stringing up your xmas lights.