When I change the encoding in my browser(s), the controls in the cart change accordingly when I have extended chars.
However, it is not consistent and looks very amateurish. See the attached comparison image.
How do I fix this in Magento 1.4.0.1? Or, is it a browser issue, and if so, how do I fix it?

How did you create your MySQL server? When you didn’t set correct collation while creating a database, you can always face of troubles. Try following :
mysql > CREATE DATABASE sample DEFAULT CHARACTER SET UTF8 COLLATE UTF8_UNICODE_CI;UT8_UNICODE_CI has many character sets.