Even if you do other tasks, the 2500K is still quite quick. Better then the old series i7 chips many of the times. Unless you need SERIOUS number crunching power, the 2500k is the best of the bang for buck CPUs.
First, the processor is the CPU. What you want to build is a system.
Second, do you prefer AMD or Intel, or does it matter?
A computer system can cost anywhere from around $400 to $4000 and up, so a base budget would be handy.