Mapping table for ’ to apostrophe.

Problem caused by cut and paste from Unicoded web site

[lierduh]

Cut and paste from supplier's web site has given us extended ASCII characters. Although we convert them to numeric entities, they still do not pass html validator. eg. "Warning: reference to non-SGML character"

I am just wondering if there is a table somewhere I can refer to for mapping these viewable extended ASCII characters to the equivelent standard ASCII range.
for example:

“ => "
” => "
’ => '
Ä => -

[chrisjoha]

From this page: [w3schools.com...]
you'll find:

" quotation mark "
' apostrophe '
- hyphen -