Problem importing photo's from Windows to OSX

Hi All,

I am fairly new to the world of mac's and i'm having a problems with my photo's. On my old windows PC I have 1000's of photo's. When i right click on a photo in windows and go to 'details' it will tell me the exact date and time when it was taken. So if i then import them into some library software such as picasa, it sorts it them all out by this date. However....I've now copied all my photo's to my new imac and the 'date taken' field doesn't seem to be there. When i import them into iphoto or picasa etc, they are totally messed up and all over the place. Why did OSX loose that data ?

Any help appreciated

/edit I will try to explain a little better using screenshots. This screenshot is from windows :

http://img510.imageshack.us/img510/1714/windowspg.jpg

At the top is says 'date taken' and ANY windows photo library software will sort it by this date. Below are the properties of the same file after it's copied to osx :

http://img153.imageshack.us/img153/6345/screenshot20100322at145.png

It contains lots of information about the picture but not when it was taken. So software such as iphoto or picasa sorts it by it's created date (which you can see at the top is Monday 12th January).

Why isn't OSX carrying over the exif data on when the photo was taken ?