Marathon training plan for sub 5:00

Hi I was lucky enough to get a ballot place in 2013 London Marathon. I am trying to devise a training schedule. It will be my second marathon. I have had ITB issues previously once I increased my mileage over 14 mi. it continued to play up throughout the latter part of my training & the race. I stopped running for a few months after the race to give it time to calm down. I recently did the Great South Run 10mi, although not in a brilliant time due to lack of running training. I would like to do London in a sub 5:00 without having ITB pain!!! My plan is to start training this month to build up my mileage slower. I will drop back & start at 5mi. Then increase by a mile a week up to 18mi dropping back by 2mi every 4th week. I will then add in one 20mi & one 22mi end march time. My question is that a friend of mine suggested I train in a 9 day cycle instead of 7 but this has confused me a bit & i cant find any 9 day cycle examples online. I plan to do one long run a week (has to be at weekend), one short 30min run, one interval session, two strength training sessions & one spin per week. Not sure how I can get a 9 day to work for me given when my long run is plus I want to stick with a spin on one set day & one strength class on another set day (ViPR/kettle bells/body pump). Given that I am starting earlier to build the mileage up slower, would 7 day still be best for me? Any thoughts, opinions or suggestions greatly apprieciated. Thanx in advance.

I'd forget anything to do with intervals, spin and focus on plenty of easy paced (i.e you can talk without pausing to breath) running  and strength exercises for probable cause of ITB - weak hip abductors.

I can't see a 9 day schedule would work for you. 7 days is better simply because you're on a 7 day timetable.

3 runs a week isn't much but if that's all you can do without getting injured then you have to go with that.

Have you addressed the ITB problem and it's causes or does it just go away with reduced mileage ?

I'd probably not bother with a 30 min run and and the interval. As Ian says - stick with steady running - but 30 mins is hardly worth bothering with. It takes 20 mins or so to warm up and 30 mins is a long way off your marathon time.

Spin can be good on a cross training day - it will give your cardio system a good workout without any Impact for you.

Some good suggestions here thanx. The ITB I am hoping is ok. The furthest I have run since May is 10mi last weekend & had no twinges from the knee. I think it was caused by incorrect trainers (I overpronate) & upping my mileage too fast. Hence the plan this time - take it steady & up the strength training!! When I had the knee pain it was only when I ran over 8mi - anything else it was fine & in day to day life. Also only came on in mara training - had no probes training for 2 previous HMs. Am thinking its best to stick to 7 days now.

Over pronation is also typically a symptom of weak hip abductors : )