Converting from GMT -> EST and Date & Time in HH.MM.DD.SS.MS format

Hello all:

I'm new to the board, but can see this being a valuable resource for me in the future. I am trying to do two things:

1. Convert date and time in this format from GMT -> EST for these dates / times.

Current format is: YYYY-MM-DD-HH-MM-SS-MSMSMSMSMSMS
2010-03-18-03.55.30.477460
2010-03-18-03.55.30.648572

2. After converting, I need to find out the difference between the two dates / times.

Would appreciate any help anyone can provide.

Thank you in advance!