HI evedawn - oooh ---- you are so lucky in the current climate to have the choice!
I've been exactly where you are, some years back. Our organisation was merging and I was interviewed for my "new" job in the new organisation and I got it. Phew. Then I saw my current job being advertised, and I wanted it so much, that I applied, and I got it. Then I had to tell my bosses, sorry, I'm not coming with you to the new place. They were not best pleased, as then they had to readvertise etc... but they recruited someone ideal for the new organisation, who filled the role in a different way to me and did it very well. I meanwhile found a job I love and which I have now done for the past fourteen years.
Think a bit about security - is the new job in a provider Trust, so has some future in all the forthcoming changes? Our PCT jobs will go anyway in 2013 when the PCTs go, so we either get TUPEd or look for something else as yet to be decided.
TBH, if you want the new job, then go for it. You will feel that others have paved the way for you to stay in the current job, and it's a bit disloyal, but it's your future that you have to think of, and the opportunities which that might bring to you as the NHS changes.
Good luck - if my experience is anything to go by, you won't regret it. Let us know how you get on!