We can not assess your past filing status ( 1040 NR or 1040), Even if you want to correct it , can go upto 2005 to amend. Mistake is done and do not know we can reverse and make it correct.

For 2008 you will qualify to file as resident. Most tax software are giving free federal efiling. There are other tax software cheaper than turbo tax.  . If you do not need to file state, then it is free.