what store, and you may need a new sim card form VZW

 

There is nothing wrong with your sim card, and whatever a vzw is it won't help you. The Nexus is divided into regional builds and a few regions have not got anything beyond 4.0.1 yet. You can either sit tight and wait until your region gets an ota or do it manually. You don't need to be rooted to update manually but you do need to unlock your bootloader which will wipe your device. There are some instructions here if you feel like going to that extreme:

[HOW-TO] Convert to latest yakju/takju build (from any other build) / Return to stock - xda-developers

 

the only way to get it until your carrier pushes it out is by unlocking your bootloader as noted above. Doing so WILL WIPE YOUR PHONE.

 

Or get a Gnex from Sprint, which is shipping with 4.0.4. Worked for wife and I.

 

I believe the OP is in Canada on a GSM version of the Nexus. Sprint version wouldn't work for them.