I also have problems w/ my Intellimouse w/ Intelieye (2 buttons + wheel).
Win2k thinks it's an Explorer and I cannot set it correctly, although I tried
the latest Intellimouse software. Sometimes some clicks don't work at all, the wheel works most of the time. I think it's a problem w/ usb. I'll try the ps/2 port when I find the adapter. Works fine under W98.