I just got the refurb black 2.2GHZ MacBook last week- the week before that 4 GB of ram was waiting here patiently for it..For the cost it really is a no brainer if you can afford it.. While you may not need 4GB for the tasks you mention, OSX could certainly make use of 2GB with that.. For a couple bucks more you can keep the OS running right along..
I have 2.5GB in my iMac G5 and just today I noticed I had 20 Page outs.. The machine was running Excel, iTunes, video chatting, mail, and safari.. Nothing too intensive, but enough that the OS found ways to utilize all that Ram and could have possibly found use for even a little more it appears.. Sure, it would have been fine with 1GB probably, but if you give it more it will make use of it and that's a good thing..