No, not overclocking. Nothing is overclocked in my system. These day I prefer stability over a few percent performance gain
The 2.4Ghz is standard for this 4000+ Single core (San Diego). Here's a screenshot of an diagnostic program (Everest home edition). This CPU is multiplier locked and as you can see it's running at the stock 200Mhz FSB.
The 4400+ is a perfomance rating. Your CPU is built differently than mine and should theoretically perform as a classic AMD Thunderbird running at 4400MHz. But as you see from this benchmark, that's not completely true, at least for single-threaded applications. In that case the single core CPU usually 'wins'.