Hello,
I've been in the US since August 2002 studying, and graduated may 2006 (F1)
During this period I filed 1040NR but never used the Hope or Lifetime credit.
Could I have applied it?

From August 2006 - July 2007 I worked on the OPT, and filed 1040NR in 2006.
I also started to apply credit for student loan interest in 2006

From October 2007 - present I have been on the H1B.
Can I file using 1040 instead of 1040NR for 2007?

Thank you!

Negative; the education credits/deduction CANNOT be claimed by non-resident aliens filing Form 1040NR or1040NR-EZ. You CAN claim student loan interest, though.

However, the 5-year exemption authorized for F-1 students expited for you on 31 December 2006. Starting on 1 January 2007, you became a resident alien.

So, for 2007, you should file as a resident alien, filing Form 1040 or 1040A. You can then claim either the Lifetime Learning Credit or education deduction PLUS claim the student loan interest paid in 2007.