is it okay to turn windows defender off if i have already installed norton 360 antivirus

I have recently installed norton 360. but before doing that i had a problem with windows defender as it said that new updates were not possible, and an error code appeared. I scanned my pc thoroughly for viruses but there were none.
All my problems were solved once i downloaded a trial version of norton 360.Now windows defender has automatically been turned off. Just one qs. is my laptop(vista 32 bit) safe with just norton 360 protecting it.

Hey!
Yes, Norton is a reputed Antivirus Product from Symantec and is one of the best security product available... Well if it provides full protection [which i don't think is available in trial version] then you need not worry...! All the best..!