update php from 4.0.6 to 4.1

[searain]

all my sites are written on php 4.0.6, now i want to update my php from 4.0.6 to 4.1 or better.

will i have problems with my old sites which were written on php 4.0.6?

some said it would. how? so if i cannot rewrite every site, that means i can not update to 4.1?

what should we do differently in programming in 4.1 than in 4.0?

should it be logical that when i update from 4.0 to 4.1, all the old sites (4.0) still work 100% fine?

thanks.

[jerdo]

If you want to be able to use your old scripts with a newer version of php without rewriting said scripts simply change the register_globals option in the php.ini to ON