apple application supportcannot be removed

When installing the latest 10.5 version of i-tunes I get the following for messages durring installation.

1) "The older version of Apple Application Support cannot be removed"

2) "The older version of Bonjour cannot be removed"

3) "The older version of Apple Mobile Device Support cannot be removed"

4) The older version of Apple Software Update cannot be removed"

The installer program then aborts installation.

Help please!

Pepperyhot