I would likely say no, but it depends on what you are using it for. Many of the core2duos have a higher amount of throughput (faster in regards to Ghz) but less bandwidth (bottlenecked if both cores are being utilized at a high rate).
If you are using multiple programs/applications that support multithreading up to 4 cores (most games now days do support this), I would likely say you will get a better bang for your buck from a core2quad in my opinion.