Ranjit,
A great tool for determining accuracy is our online accuracy calculator. The total system accuracy will also be a function of which DAQ board you are using.
Accuracy Calculator
http://www.ni.com/advisor/accuracy/
This page will also help with understanding all of the accuracy terms.
http://www.ni.com/support/calibrat/accuracy.htm
Regards,
Justin Britten
Applications Engineering
National Instruments