I'm so glad I found this thread as I've been experiencing exactly the same problems as Tamara.
I've been dabbling with running for the last 6 months (mainly to compete in triathlons/duathlons), but have been so sporadic and undisciplined that every run feels like the first time. My heart rate rockets, my pace never increases, etc. etc.
I start with the best of intentions, then lapse for a few weeks and maybe a month or so, then pick back up at the beginning.
The run/walk method also feels like failure - even though all the cycling magazines/websites recommend it.
One thing that I thought was interesting, after reading the Runner's World handbook, was that measuring your runs in minutes, rather than miles/kilometres was a better indicator for training. This stops you being focused on pace and, for example, trying to run 5 miles within a set time limit.
It also states that you shouldn't increase your running by more than 10% per week.

For me, I know that consistency is the key. I need to develop a base running fitness to progress - just as I did with cycling. I find it frustrating, however, that I've reached a reasonable level in cycling, but this hasn't carried through to the running, and one discipline doesn't gain you automatic results in the other.

Ironically, I've now competed in all the running events I planned to do for this year (managing to somehow wing my way through them), and winter is drawing near here, but I'm even more determined to crack the running for next year, so will be upping the training through the dark mornings/nights and the colder weather.
I want to be able to incorporate hills and intervals into my regime, but feel that I need to be able to at least run for 30 minutes at a fresh, easy pace, before I should try. Is this realistic? At what point should you introduce additional stuff into your training?