I made the transition from heel striking last year, I'd only been running a couple of months when I did it though so I didn't have years of heel striking behind me. I did it very gradually, the first 5 minutes of every run, then the next week the first 8 minutes, the week after that the first 12 minutes and so on. It felt very odd at first and my calves didn't like it one bit. I reckon it took around 6-8 months for me to feel totally comfortable with it but once it does you'll never look back.
Flatter shoes help (I run in Saucony Kinvaras). Stick with it, you'll be glad you did.
I'm coming to the end of a 10 week beginners run/walk program and am wondering what to do next. I want to carry on following a program of some sort as I enjoy the discipline. I have looked at a few 5+10k programs but they all include speedwork and I've read on another article on this website that you shouldn't do any speedwork until you've been running for at least 6 months. I'm probably going to enter one of the Parkrun 5k's in the near future and hopefully build up from there.