I am running an intel 1.3 celeron on 384MB of ram at work.. it is an old PC and really really out of date. However, as I type this, I am running Photoshop CS, PSPX, using Firefox, have 2 work applications open and am hosting a sql server on this very old PC.. and.. have no issues.

My point - ANY PC can run these applications - even multiple ones - with ease. Granted, if you have the ability to buy the dual core.. by all means - it is a decent system choice. But - if you really want to test your system.. try encoding a DVD and running photoshop or rendering a large 3D image and running photoshop. That's truly where you will notice the impact of a new system... even though photoshop is a large (and memory hungry application), it still will not push your system like these other applications will.

Just my 2c...