Photoshop loves ram!!! So yes it would definitely be faster. You would of course need a 64bit version of Windows. You will likely be replacing the existing ram, so I would stick with DDR3 1333 from either Corsair or Kingston. Just double check your machine's web site to make sure it can handle such an upgrade. The processor itself can handle up to 16gb according to Intel
If you do not yet have Photoshop, you can download a free trial version from the website. http://www.photoshop.com/products/photoshop
If all you are doing is light editing, then your current setup may be good enough. Either way you will know before shelling out for PS.