String replacement for all files in directory

[Kipton Moravec]

How do I do a simple string replacement of one string with another
string in all files in a directory?

For example:

I have 1200 files in a directory. Wherever I see the string
"footprint=0603C" in any of the files (may occur 0 or multiple times) I
want to replace with "footprint=CAPC0603N"

I do not know how to figure out what command to use so I can look it up.

Kip  
-- 
Kipton Moravec AE5IB
"Always do right; this will gratify some people and astonish the rest."
--Mark Twain