"Iron" theme.

If you're buying it for home use, I'd recommend a dual-core processor. Let me explain: most games these days are optimized for dual cores. Plus, older games (like F.E.A.R. or Oblivion) don't support multi-core processing and will only run on one core. Moreover, the E8400 is powerful enough, and its potential will last for a long time, including the era of quad-core processors. There aren't any games right now that will fully utilize the potential of the Q6600 processor. If you're worried that the era of quad-core processors is coming soon, even if that happens, the Quad Q6600 will still be relatively weak, plus there's the issue of compatibility with older games. Choose what's available now.
to WitcheR-L, I think the person is leaning towards a decision, also considering the financial aspect.