Hi. Did you try to install Photoshop Touch from the Android Marketplace?
If so then I have a couple of questions.
How largre is you samsung galaxy? What Android version do you have running?
I suppose you are using the Samsung Galaxy Tab.
Normally if you can install it over the Market Web interface it should be compatible - you shouldn't even be able to see it in the Market app unless you are compatible.
Do you get the error from the Market application or when trying to start the application - i.e. does the application exist on your device?
It would also be good to know the exact model number as well as language you're using and what country your in.
What you could try out would be to clear the Market cache and then retry the install.