Merge address in XL to Word letter template

Friends,
Here is the basic situation. I have about 10 excel sheets containing addresses of thousands of contacts. They are written like this:
[Prior Title][First Name][Middle Name][Last Name][End Title][Street Address Line 1][Street Address Line 2][Street Address Line 3][City, State Zip]

Not all cells, like titles, contain data for all persons. Anyway, what I need is a way to insert, automatically, these addresses into the proper address space in a prewritten letter and on an envelope. I know how to merge to create address labels in word, but not merge them into a completed letter, as in:

Word File:
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December 7, 2005

[Prior Title][First Name][Middle Name][Last Name][End Title]
[Street Address Line 1]
[Street Address Line 2]
[Street Address Line 3]
[City, State Zip]

Dear [Prior Title][First Name][Last Name][End Title]

How are you, blah, blah, important stuff, blah.

Sincerely,

TheOne
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So, one letter, thousands of different addresses. What do you folks think I can do to achieve this? Any suggestions, except for how to make normal address labels, would be greatly appreciated.

Thanks,
TheOne