S95 video files lose date when imported

I'm stepping into the HD world finally. I have several sources that will shoot HD of varying quality:
Canon S95
iPhone 4
Nikon D90
Sony HDR CX550

The question is what date is attached to the video files once they are imported into the computer. All of the files from the cameras EXCEPT the Canon retain the date the file was filmed when the file is imported into the computer. The Canon is the only one that tags the file with the date the file was imported. I've tried turning on all the other Date stamps that I can see and they are ALL the import date.

Why is this...and how can I get the S95 files to show the date the video was taken vs. the import date? My goal is to sort them all by date taken so that all of the file clips line up chronologically regardless of which camera was used to film each clip.

...and to add a bit more info.

I am using Windows 7. I have been copying the files off all those cameras using simple drag/drop within Windows. I haven't used any of the proprietary software that came with the cameras.

Would using Canon's software that was included with the camera fix this date problem?

it might be that the canon doesn't set date/time stamps? On your camera, make sure the date/time is set.

The date is set...and it tags the EIXF for photos just fine. And when I view the files on the camera through the computer the dates are correct. But when I transfer the videos to my computer the date for the file as changed to the date I download the files to the computer...that's the problem.

hmm, that's certainly weird. If you're making the transfer in Windows Explorer then it's an explorer setting issue.

oh, are you copying the files over, or moving the files over?

I copy them...would that matter?

I tried MOVING the files over vs COPYING and the results are the same. The file date (even the CREATED tag) is changed to the current date on which you moved it over. This does not happen for photos...only videos. Very frustrating.

Just as a follow up...in case someone has this problem in the future.

I learned that if I copy (or move) a video file directly from the camera via USB in Windows 7 it changes the file date to the date the file is moved to the computer...but if you use a card reader to get the file from the camera's card into the computer the file date is left unchanged.

very weird.