How much internet usage (GB) will it take to download iOS 5.1.1?

I am not sure how much data needs to download iOS 5.1.1, but I can assure you that it will not take more than 1GB.

It is 156 mb for your fyi..................

the 156 is the incremental update when you do if via wifi on the iPod.

If you do the update via iTunes you download the complete update file and this is about 0.8 GB

lllaass, I am using ipod touch Ios 5. I want to upgrade to 5.1 I have the videous and songs in it. It ask me for upgrade 5.1 in itunes should I just instal it? WIll it remove all my songs and videous if I install ios 5.1 when it asks for upgrade in itunes? Please help.....

If you have not yet upgraded to 5.1.1, don't. There is code in the upgrade which causes charging issues. Chargers and USB cables which worked perfectly prior to applying the update stop being able to charge the device. This problem appears to be widespread, just google "Charging is not supported with this accessory" and you will get 350,000 hits.

For my own experience, my daughter has an iPod Touch, and my wife has an iPad (original). Both were upgraded to 5.1.1, and now neither will charge. I have 2 different chargers, and 4 USB cables. Plugging either device into my laptop (Win7), my desktop (Win7), or the wall via the chargers all come up with the same error. All cables and chargers worked before the iOS upgrade. My niece has a Belkin charger, am going to try that next.

Do yourself a favour, stay away from 5.1.1.