Pentium Pro-blems

Hi, I have a pet project most of you will find interesting, and I've run into a block that some of you can help me with. First, here's the specs on my system:

• Two Pentium Pro, 200 MHz/1 MB cache oc'ed to 266 MHz
• 512 MB 5v 168-pin 60ns EDO RAM
• 100 GB 7200 RPM IDE hard drive
• 32 MB ATi Radeon PCI video card
• Windows XP Pro Service Pack 1

I get about the same performance as I would with dual 300 MHz Pentium II chips if you disregard the bus speed differences, and I have been very happy with this system so far. One thing I would like to do, however, that I think will improve system performance is to upgrade to 1 GB RAM. I notice some serious redraw problems and a lot of swapping going on, and my CPU use is always at at least 15%, and simple tasks like moving windows and editing HTML spike it to 70%. Real intensive stuff drives the CPUs to 100% max for longer than I feel it should. Kernel time is a significant proportion of this.

The IBM docs on this machine say it can be upgraded only to 512 MB, using 128 MB chips, but I have found RAM that matches the physical and eletrical specs to a T save for that they are 256 MB chips.

Does anyone have any experience with this? The motherboard is from an IBM PC 365.

Thank you.