What are my chances for any of the old IIM's and XLRI with the above profile 10 the - 79%, 12th- 60%, B.Tech -77%, work experience - 1 year?

In order to get into one will get into top-notch IIMs like IIM Ahmedabad, IIM Bangalore, IIM Calcutta, you need to score around 99 percentile in the CAT exam. If you have secured a decent score and your own work experience, then you will surely get a call letter from any of the above IIMs and XLRI also. 

Old IIMs - All of them have weightage for Academics, but they aren't your strong point. 

XLRI & FMS - They don't give any weightage for your Academics in their shortlisting process. So you do stand a chance there. But it's advisable to focus on the CAT exam, the above percentages in 10th,12th, and during B. Tech is necessary but not mandatory. Aim for at least 99.5+ percentile in CAT. 

For example, Chetan Bhagat, who is the writer of some novels, said in his novel 'Five Point Someone that he just got a CGPA around 5 in mechanical engineering. But he did his post-graduation from IIM Ahmedabad. If the academic background is that important, he would not have gotten into IIM Ahmedabad. But it would be really difficult to justify your poor academics although it can be done.