Itunes

i have a ipod nano that is assigned to my itunes..i havent downloaded too many songs but i now acquired my friends ipod touch so i want to use this ipod now on my itunes instead of the nano.. when i plug it into my computer itunes recognizes it but asks if i want to sync and erase new ipod.. my question is.. will i lose all the apps that i have on the ipod touch as well ?? i dont care about the music because my friend has music i dont even like it's the apps i dont want to lose ?? please help