That all depends on usage.
everyday use? No its not worth it at all. You're better off with an Athlon64 unless your heavy video editing, in which case a P4 3.4GHz or more will also do.
servers? Yes thats what they're designed for and will work well. But remember you also have the option of an AMD Opteron CPU aswell.
Gaming there is no point, most games are not multi-threaded properly and Athlon64s are much better for gaming.