I think, based on what you said you are doing, that level of battery drain is probably to be expected. You're basically running the machine flat out the whole time, it never has the opportunity to use any of its power management tricks.

For that level of use (Photoshop, Photo previewer, Acrobat, and multiple Word docs all simultaneously), I think 5 hours is OK, but I don't know for sure.

Here's one thing you can do. Do a refresh, which will let Windows clear all the updates and patches, clean the registry and subsystems. Let Windows re-download and install all the updates and patches. It's always a good idea to clean the system once in a while.
The downside is that anything installed from CD/DVD media will have to be reinstalled (Office, Acrobat, Photoshop), but all your files (docs, photos) are preserved.
But if there's any more battery life to be had, that's the way to find out.