I installed the disk and it all went well. I have a 64bit Dell machine and there in lies the problem. I was prompted to check a box to load the 64bit version and/or the 32bit version. I check both and in fact, both versions were installed. Great. I clicked on the 64bit version and CS5 opened. I did the same for the 32bit version and got a error message that the application failed to start. I had to clicked "OK" 3 or 4 times and that version opened. OK, so no problem, I'll just use the 64bit version. I went into my files and transferred all my "plug-ins" from CS4 to CS5. Checked my work and open CS5 64bit version. No "plug-ins" appear in the filter menu or anywhere else. So I go back and transfer all the plug-ins into the 32 bit version and open that. Get the error message, click 4 time, the program opens and all the plug-ins are there. It hits me that my 64 bit Dell does not support any of the plug-ins.
It should be interesting later today when I call Adobe tech support to try to straighten this out. Stay tuned.