Timezone functions?

I am working on a project that I have to convert the date/time to different timezone include daylight saving time (DST). This project will be on a Windows server for a lot of the functions I have found on PHP.net don't work right. I am storing all the dates on the database in GMT time, thus I take the users input dates and convert them to GMT based on their timezone. Plus convert from GMT to their timezone. I would also like a function that can tell me to offset with DST. Example; I give it EST it would right now return -4, not -5 because of DST. I have looked a the PEAR Date_TimeZone class, it looks good, but there is no doc or examples on how to use it. Can someone recommend some good functions to using, that work on a windows platform. Thanks, Mark.