I have been using Flipkart for over a year now. Mainly bought books from them, but I have also ordered software and external HDD from them.
But I am really happy to say that they have delivered the product within 2-3 days on each of the occasions. Also, never faced any issue with the quality of the products.
I would highly recommend Flipkart to everyone. I have tried other websites like Rediff, Indiatimes, Infybeams etc earlier, but Flipkart seems to be the best in India at this point.
One more thing, no matter which site you buy from, never go for Indiatimes. They are thieves.