OK - as someone who uses PS CS4 on a daily basis, can answer a couple of questions:
PS CS4 x86 x64 are two completely separate entities - no interaction btwn any components.
That being said, there is a good reason that at this point the x64 build installs both environs... 3rd party compatibility. In my case, I have a scanner which lacks nesc components to interact with PS x64, thus have to use the x86 version to import content from scanner. Also, some filters/plug-ins also not compatible with x64 version. Thus, by giving the user both versions, they are allowing you that fall-back if you need it.
I read what you said that both photoshop CS4 X64 and X86 does not interact. And this is right that some plug in are not available in X64. so here is my problem the default program to open psd file is photoshop CS4 X64 since my operating system is windows 7 ultimate X64. I cannot change the default opening to photoshop CS4 X86 I do not know why. And my plug in from eyecandy company can not be installed cause of the X64 version. Is there a way to keep only the X86bit version??
could you help me please
thanks in advance