Quoting the Apache documentation here:
I would suggest using the correct meta attribute in HTML for the character set you are using, rather than setting this in the web server globally.AddDefaultCharset should only be used when all of the text resources to which it applies are known to be in that character encoding and it is too inconvenient to label their charset individually. One such example is to add the charset parameter to resources containing generated content, such as legacy CGI scripts, that might be vulnerable to cross-site scripting attacks due to user-provided data being included in the output. Note, however, that a better solution is to just fix (or delete) those scripts, since setting a default charset does not protect users that have enabled the "auto-detect character encoding" feature on their browser.
This link explains how to do this: http://www.w3schools.com/html/html_charset.asp
I believe the normal charset used on Linux systems is either ISO-8859-1 or UTF-8. On Windows systems it is probably ANSI (Windows-1252) or UTF-8.
According to that page:
Ultimately it probably won't change the web page you're displaying if you already specify the charset to use in HTML.If a browser detects ISO-8859-1 in a web page, it defaults to ANSI, because ANSI is identical to ISO-8859-1 except that ANSI has 32 extra characters.
I agree with TrevorH though, using special ANSI characters in your HTML should be avoided. It might be possible to use the awk or sed commands to update all your web pages at once from the command line. I would suggest doing that rather than defaulting the server to ANSI mode.