I could not DISAGREE with Sheila more - no, no, no! If you freak out and get angry and stressed, your kids will freak out and get stressed and you'll be potty training 5 year olds (somewhere in between counseling appointments, I'm sure). All kids are different. The more you try to force the issue the more fight you've got on your hands (sounds like x 2 for you). Be patient, this too shall pass ;)
I put the kids in underwear and then put a diaper over it. When they went, they knew right away and recognized that they didn't like the feeling of being wet. It also gave them the satisfaction of wearing underwear, but saved me from cleaning up puddles or changing outfits 15 times a day.
We tried the turn around backward appraoch too and I think it was a good tool. It elimates a lot of the fear of falling in and minimized the mess from misses. We also had both boys sit down to pee. It's easier to get them started that way - they can master standing and aiming later on.
For boy number 2 we bought a potty chair that looked like a prince's throne and played music after something hit the bottom. It was a nice reward when he got the job done.
Our first son was pooping on the pot at 18 months, but would happily sit in a dripping wet pull-up all day long. We took what we could get and encouraged him to try once in a while. At 3 yrs, 3 months we were packing for vacation and he came in and announced that when he was in California he would wear big boy underwear. Off to the airport we went, underwear on and a change of clothes in the bag just in case. He was fine the entire airplane ride and has been ever since.
Our second son pretty much potty trained himself. He was over it and wanted to go to school, so at just over two the diapers came off. He had a lot more accidents than his older brother, but nobody freaked out and it regulated itself in a reasonable amount of time.
We're working on our daughter right now. She turned two in January and has ZERO interest in sitting on the potty. Whatever... we'll get there (and so will you).