Yes, what does the rest of your system look like? And what do you plan on doing with your system (i.e. why the upgrade)?
If I'm not mistaken, the 170 is 2.0ghz and the 4400+ is 2.2ghz. Both should overclock well, if you're planning on doing that. But for $6, flip a coin. In fact, save almost $50 more and grab an X2 3800+ and overclock it. You likely won't miss the lower cache, again, depending on what you'll be using it for.