Thought everyone might like to know this.
 
 October 2009
(Week 1): Necrosha One-Shot
(Week 2): New Mutants #6

November 2009
(Week 3): X-Force #21
(Week 4): New Mutants #7

December 2009
(Week 5): X-Force #22
(Week 6): New Mutants #8
(Week 7): "Necrosha: The Gathering" *
(Week 8): X-Men: Legacy #231

January 2010
(Week 9): X-Force #23
(Week 10): X-Men: Legacy #232

February 2010
(Week 11): X-Men: Legacy #233
(Week 12): X-Force #24

March 2010
(Week 13): X-Force #25
 

Best line-up to get involved with the story eh?

Not best, only. That's the order you have to read them in, each one continues where the last one left off. Like with most x-men crossovers.

Ah.

Yeah, we already know, thanks. 
 
@xerox-kitty said: 

" Here's the official line-up of Necrosha involved issues: 

 
October 2009   
Week 1: Necrosha One-Shot
Week 2: New Mutants #6 
 
November 2009 
Week 3:  X-Force #21
Week 4:  New Mutants #7
 
December 2009 
Week 5:  X-Force #22
Week 6:  New Mutants #8 
Week 7: Necrosha: The Gathering 
Week 8: X-Men: Legacy #231
 
January 2010 
Week 9: X-Force #23
Week 10: X-Men: Legacy #232 
 
February 2010 
Week 11: X-Men: Legacy #233 
Week 12: X-Force #24 
 
March 2010 
Week 13: X-Force #25 
 
This doesn't seem to include the annuals.  It surprises me that it's going on for so long, but it seems to drift in & out of different titles.  So it effects New Mutants earlier than X-Men: Legacy and it effects X-Force for much long than the other two titles. "