I maxed out to 2GB right away, so I don't know how the performance is going to be with 512MB. However, based on memory usage(and the fact that it uses some[I think 64MB] of your system RAM for video), you'll want at least 1GB. I got my RAM from [link|http://eshop.macsales.com|OWC]. They currently have 1GB for $110 and 2GB for $215. Upgrading the RAM was easy, so you can always get it with 512 and upgrade it later.

I watched a movie, just shy of 2 hours, on the flight to my brother's for July 4th. There was enough battery life remaining that I could have watched it again w/out any problems. I'd converted the movie to a 1.5GB file using Handbrake and had it loaded in a RAM drive, so the hard drive and DVD were not active.

My Thinkpad was having issues, so I purchased the MacBook as a "placeholder" until I could afford a MacBook Pro next year, but now that I've used it a while I don't see the need for the Pro. I'm now looking at replacing my iMac G5 with a Mac Pro next year instead. That'll disappoint my dad, he wants to buy the MacBook from me when I upgrade the laptop.

The appearance of the keyboard initially reminded me of a chicklet keyboard from an 80's home computer, but it works and feels just fine. I was concerned enough about the keyboard that I went to a store to try it before I ordered the MacBook.