I agree with Kakaze... The macbook should fit the bill for those tasks just fine. Probably 1GB RAM -- 2GB isn't a whole lot more and would probably be overkill, but then you also wouldn't have to worry about not having enough for most Photoshop and video editing tasks. The only weak point of the macbook is the integrated graphics... But the newer Intel graphics chips aren't all that bad for most general things and it's powerful enough to handle games like Halo or Quake3 and even some of the newer stuff. Unfortunately, not too many games are available as universal binaries just yet, so gaming on the new Intel Macs is somewhat of a sketchy proposition. Of course, you can always dual-boot Windows and play games that way... Games don't really work through Parallels, or at least not any that require direct access to video functions outside of the Windows GDI.
I'd recommend stopping by an Apple Store or CompUSA or some place that sells Apple systems and taking both the Macbook and Macbook Pro systems for a test drive. Most Apple Store locations are very good about demonstrating various applications, even third-party software (to some extent) and you should be able to determine if the Macbook will handle your needs. If the Macbook fits the bill, then go for it. It's a lot less expensive for the same amount of CPU power, all you're sacrificing is 2" of screen real estate, an Expresscard slot and a dedicated graphics chip. Sounds like a lot to give up to save a few hundred $$$, but if you don't need them, then the macbook is a great deal.