Solo questing yes, but when you enter raid instance or battleground your FPS drops to 4, not 40.
If you want honest view of what crappy $400 laptop can do in a multiplayer environment create a character in high population realm and walk into Stormwind or Orgrimmar. Of course if you're happy playing it as single player game then the requirements are much lower.
Is that good reason to drop $500 on something that cant be upgraded or sold in a year from now? That's really poor way to spend money when you ain't got any.