About a month ago I rebuilt my wife's computer and did the first completely 'fresh' OS install in several years. I had a slot-1 750 and a P3B-F that was still new in the box (bought it like 2 years ...

Since your computer isn't ACPI compliant that means you don't get the convenience of automatic hardware powerdown after you shutdown Windows. What motherboard do you have? Sometimes a BIOS update can ...