I concur...the dual-core X2 3800+ is roughly equivalent to a single-core 3200+ when it comes to games, or at least that's what the majority of benchmarks around the web have shown...
My advice, if you're heavy on the gaming, stick with a single-core solution for now. Until developers can harness the power of a dual-core setup, single-core CPU's will continue to take the top spots for gaming.