How about just erasing the resolutions from powerstrip? I know that once I add the resolutions in PS I can exit out of it and using QuickRes from ultimarc I can change to whatever resolution there is. I believe you might be getting a bad desktop on boot from powerstrip since it has a bug that it won't drive the arcade monitor correctly even though you have it set at the right resolution. To solve this, just add the resolutions you want through PS, then it'll ask you to reset the pc. For now, let PS start on boot, and once it starts, turn PS off and use QuickRes to change to that desired resolution you just added and plug in the Arcade monitor. You should be able to get windows to display in a 320x240 non interlaced mode at 15 kHz without a problem. Once that works, you can set PS so that it does not start on boot, and windows should boot up in the last resolution it was set in, in this case being 320x240 or whatever. This worked perfect for me using the same monitor you got, a Radeon 9200SE and the latest catalyst drivers.
I wasn't really sucessful at getting AdvMame to work today, any tips on how you went about doing it?
Hope this helps, Fred.