The upgrade from 2.4 to 2.6 is a special case, because a lot of modules have been renamed, the module dependencies have been changed, etc. Guessing the list of modules to load for 2.6 while 2.4 is running is pretty error-prone. It is more safe to install some additional modules.
If you rebuild the initrd from within 2.6, then the additional modules will be gone (hopefully). But please make sure that you can boot a backup if you try.
Regards
Harri
