smp, FWIW I just set up an EPoX 4SDA+ board (SiS645 chipset) w/ the High Point 372 onboard controller, and it was simpler than simple <g>. This is on a Windows 98 SE box. I had some trouble w/ 98 over the weekend and I did an install of Win XP Pro, and that was equally simple, re setting up the High Point controller.
One thing to watch for, and that's the ability of the onboard controller to act simply as an additional disk controller. I believe that certain versions of the Promise onboard solution do not allow that.