People treat WoW like it needs a 7xxx series GeForce or better to run. It doesn't. If you're smart about it, turn the texture settings to low, AA/AF off, shaders off and keep the draw distance fairly low. It's the textures that can kill it, since the GMA950 uses system RAM and therefore it's much slower and more limiting. As long as you have 2GB+ RAM though, it won't be unplayable.
WoW should run fine if you're modest about the settings; you might get some slowdown in 25 man raids with a lot going on, but that's just how it is. For most other areas in the game it should be a non-issue. If he plays WoW fairly seriously, then I would advise getting the MBP though. It will make a substantial difference to the playability in busier/more hectic environments.
Now, if you were trying to run say, Doom3 or Quake4 on your MacBook, *then* I would chastize you, but WoW, well no.