I am on TN and filed I-140 under EB2/NIW that got approved in 4 months (May2010-Sep2010)
Filed I485/EAD/AP that got approved in about 4 months (Dec2011-April 2012)
I want to thank to all on this forum and those who shared their cases here and especially Nelsona, Curious George, RealCanadian for their value able suggestions and answers. I could have not dare to apply for GC while on TN but all of you gave me the confidence that a TN visa holder can apply for GC.
Once again thank you all for your help.