I couldn't think of a good way to phrase this question for Google so I'll take a shot here.
I'm running Photoshop7 (32 bit app) on Vista Ultimate64 with 8GB ram. Photoshop lets you select how much of the available memory you allocate to it, but it only shows around 1.7 GB free. All of my drivers are 64 bit and I don't have other 32 bit apps running. I want to know if there is a way (similar to PAE) to force the OS to use the higher memory and leave the lower 4GB for 32 bit apps.
If you don't have an answer but know of a good Vista support group, tell me.
PAE isn't available in Windows desktop OSes anymore... only server. Seeing as you're running 64-bit, the whole idea is moot anyway. PAE only works if you have drivers and software to support it. If Photoshop isn't PAE capable, then having the capability would be usless, as Photoshop would still be restricted by the limits of 32-bit addressing. I'm not sure if PAE-aware 32-bit apps would be able to make use of more memory under 64-bit or not.
Basically, if you want Photoshop to utilize your memory, you'll need a 64-bit version of Photoshop. (As per the previous poster's suggestion). Even if you could enable PAE somehow... there's no guarantee that it would work.