My parents on their 1st visit were with me from August 2006 to Feb 2007 (6months) , and on their 2nd visit they are with me from Spetmber 2008 and will be leaving on June 2009 (I got the required approved extension). On both occasions I have been supporting them for alll expenses.
For 2008 they do not complete substantial presence test, but as per my understanding they qualify for the First year Choice (as per the content in the mentioned links )
http://www.irs.gov/pub/irs-pdf/p519.pdf
Your U.S. Tax Return: Substantial Presence Test (http://taxipay.blogspot.com/2008/04/substantial-presence-test.html)

Please confirm if my understanding is right. If they qualify for the First-Year choice can I claim tax refund for them for 2008

Please advice me ASAP.

Thanks

First Year Choice is not for this purpose. It is for filing Dual Status return or for filing joint return as residents.