fuck this job.com

Okay I am an attorney and I know that attorneys all have a bad reputation for being assholes, but in my case it's not always true. I tend to give people several chances before I just completely start becoming a jerk.
Well there is this secretary/paralegal in my office, my secretary/paralegal that does absolutely nothing all day long everyday. Oh wait! She does manage to do something during the day and that would be talk on the phone all day to her best friend, who calls constantly. The main problem for her is that she never follows up with things. She makes serious mistakes on every single document that she drafts for me and although she is supposed to wait for my approval before she sends it out she never does. I'm her "boss" although I have no power whatsoeer to fire her. I don't really want to fire her I just want her to do her work. For heaven sakes get off the phone and pay attention to what you are doing!!!! Everyone in the office knows that she does absolutely nothing and everyone knows that if she does manage to get something done it's going to be wrong. She used to the paralegal for my boss. I just want to scream and pull out my hair. Seriously I have to micromanage this girl if I want her to get any work done, meaning if I want her to send out subpoenas then I need to tell her to send them out and then a few days later ask her if she has done them and then a few days later ask her if she actually sent them out and then a few days later ask her if she followed up with the process server to see if anyone got served. Hell if I have to put that much effort into it I might as well do it myself! Quite honestly though I don't have enough time to micromanage her that way. I can barely keep up with my own stuff (trials, motion hearings, docket days...etc)and I've already taken on some of her work already since she can't seem to keep up and I need the work done to move my cases along or I end up looking stupid in court! She screwed up one of my boss's cases so bad that that day he came back to the office and told her she was no longer going to be his assistant. That's when I got her which amazes me because if she was just as bad then he should've fired her then. All this tells me is that no one is going to fire her and I am stuck with her.
I have been so patient with her lately and I am about to lose it. For about 1 and a half now I have been calm, nice and dipolomatic, but I don't know what else to do at this point. I refuse to drive myself crazy screaming at her, but I can't keep doing her work and mine. Any suggestions?