Hi Cindi - I use my Palm Treo with the eKey. I don't know about the Windows version, but the Palm works okay with the eKey. There's a little bit of funkiness - my phone reboots every night when it automatically syncs. I've had trouble when I'm using the key function and a call comes in - sometimes it freezes and I have to remove and replace the battery to get it going again, but that's a pretty rare occurence. In the past 2 years, I've had to reinstall the Supra software three times - the phone got into a loop where it kept rebooting in the middle of a sync and wouldn't stop. I was using a Palm Zire as my key opener prior to using the Treo. I've found the use and overall reliability to be about the same between the two.