I am also looking to do Silicon Valley Marathon on Oct 31st, but have been training for triatholone race for this weekend so I have not put in too much time in running for the last few months.  The longest I run recently was 8 miles last weekend.  I just came across this article http://www.active.com/running/Articles/4-Steps-to-Condense-Your-Marathon-Training-Plan.htm  I think I can modify this plan a little to make it a 5 weeks training plan for me.  See if you can use it and apply to your training for the last 5 weeks.  Good luck!