I am also having this problem. I am using a Dual Core PowerMac with 3gb ram and lots of space as well - but with OS 10.4.3. I am trying to update 7.0.0 to 7.0.5.

I did as suggested above and downloaded the 7.0.5 Professional update - E,Fr,G and J.
I still get the message that "my selected application version is outside the range that can be updated with this installer". I am selecting "Acrobat 7.0.0" in my Applications folder on the hard drive I have it installed on. I am perplexed.

My Acrobat is a part of CS2.....any help extremely appreciated!