APM and ATX

Hi
i have a M715 motherboard, that i have been using with a standard at type power supply, i have just installed an ATX supply. I used the reset swith to attach to a jumper on the motherboard for soft power on.
But when i select shutdown in w2k the system just restarts, instead of powering off, and in win98, it does much the same thing.
does anybody know if they have succesfully used an atx supply with the above motherboard??

regards