ios 7 and itunes

it is not acceptable that my iphone 4s could download ios 7 without warning that itunes 10.6.3 is "over". My two G4 computers are not able to download itune 11, so i loose the synchronisation of my adressbook and calendar... I use all sort of Apple computers since 1983 and never had such a problem. I cannot go back to IOS 6 and now ? Buy two new computers ?