Thank you very much for the information and reply. Yes, I installed Avast without removing Kaspersky and its working good. Still I would like to remove Kaspersky as it shows the dialog box to purchase the product (the key I used to install has been blacklisted). When it shows this dialog box often, my PC perfomance becomes low. Also, i have 256MB RAM.
I will try your suggestion over this weekend and let you know!