Where can I buy a pentium 4 2.4C processor with m0 stepping?
Specifically, I'm looking to purchase this from an online retailer
that will accept Visa, and preferably ship to an FPO (military)
address. The ship-to address is not nearly as important as locating a
site that will guarantee the stepping on the processor.

Hi strife88888888,

Here you go - I found one store which meets all of your requirements. 

1) AZZO Computers & Electronics: 
"(In Stock!)
Intel P4 2.4C (with the new sought after SL6Z3 m0 stepping) 512k cache
w/ Hyper Threading (800MHz Bus) S-478 Northwood Retail" $199.99. Visa
- yes.
http://www.azzo.com/af4/details.asp?ProdID=722

Shipping:
"Any APO's, etc. must be able to be verified and will be sent out via USPS."
http://www.azzo.com/af4/shipping.asp

Guarantee:
"Products that have been un-opened and un-used may be returned to AZZO
Computers within 7 days of invoice date, although such returns will be
charged a 15% restocking fee."
"Defective products will be replaced only within the first 30 days of purchase.
After 30 days, product is covered under manufacturers warranty unless
a longer or shorter warranty is stated."
http://www.azzo.com/af4/returns.asp

RESELLER RATINGS: AZZO
Customer Satisfaction   
Six-Month Rating: 10.00
Lifetime Rating:  8.44
Elite Customer Excellence Awards: Gold
7.50  Pricing of Products and Services
7.50 	Likelihood of Future Purchases
10.00 Shipping and Packaging
0.00 	Technical Support
0.00 	Return or Replacement
http://www.resellerratings.com/seller1770.html

I did find one other store that has the SL6Z3 listed for $175, but it
did not meet all of your requirements (non-returnable, doesn't mention
APO, store policies viewable only after starting the ordering process,
etc), and it's not listed on ResellerRatings. If you'd like their
link, just let me know.

Additional Link:
 
AZZO Computers & Electronics:
"Intel P4 2.8C (with the new sought after SL6Z5 m0 stepping) 512k
cache w/ Hyper Threading (800MHz Bus) S-478 Northwood Retail $221.99":
http://www.azzo.com/af4/details.asp?ProdID=826

>>>>>>>>>>>>>>>>>>>>>>>>>>

I hope this is what you are looking for. If not, or if you have any
questions, please post a clarification request before closing/rating
my answer and I'll be happy to respond.

Thank you,
hummer

Google Search Terms Used

SL6Z3
pentium 4 2.4C m0 stepping
SL6Z5

I also searched ResellerRatings.com

This was a very, very good answer to a relatively difficult and
specific question. (IMO) Thanks for answering so promptly.

Dear strife88888888,

Thank you for the nice note, rating, and tip - how nice of you. I'm
very happy to hear that you found AZZO suitable - enjoy your new
processor! Sincerely, hummer