1 GB total RAM is a good starting point for most users.
When Apple is upgrading you to 1 GB total RAM, they are only selling you an additional 512MB's of RAM
If you are a heavy user, you'll be better off buying the MacBook stock adding 2 single 1 GB RAM DIMMS 3rd party selling or saving the original 2 X 256 MB DIMMS.
You also need to think about a backup drive.
Your digital life will be on that notebook so I'd be sure to have safe copies of everything that matters.