Photoshop, and most video editing progs are workstation progs. If you use these a lot, an X2 may be ok for you. Just understand that games will run slightly slower. You could make that up by getting a better gfx card.
If the main use is games, a 3700 is faster than an X2 3800. If the main use is photoshop/video encoding the X2 is faster.
If they are equal use, get the X2 and a better graphics card.
In gaming, a better graphics card will usually do more for you, than a faster chip.