Keep in mind they use different motherboards, and I would pick the newer cpu if you are building a new system. First of all newer means a 5 to 10% performance boost over older generation, so the worst case is that the 4440 will be at the same speed of the 3550. I'd also probably pay a few extra dollars and get an even better cpu, seriously what is the difference between this i5 and the best i5 out there? 40$?
Also there are motherboards that can run fourth and fifth gen, so if you go down that road you can change your cpu in 2 years to something very powerful.