Hi Darshana, the 500a is still superior but with both SD and HD the difference is small. Plasma still has the advantage over lcd with fast motion and the Pioneer should maintain a higher moving resolution than the Sony. Certianly on the test we have done Pioneer has the edge.
The Sony is still very good though and without seeing the latest offering from Sharp ( the XS series ) I would say it is the best LCD screen avaialble. I am yet to find something that the Sony does badly, it excels with SD, DVD, HD and bluray but is is just that one crucial step behind the Pioneer. Even the size doesnt help its case as the 55" we have is the same size as the 600a without speakers at the same price!
Nick
Nick