I recently started using the SyntaxHighlighter Evolved plugin on Webmaster-Source. The plugin provides an easy way to format code snippets for display in posts, complete with colorization.
When using SyntaxHighlighter Evolved, you don’t need to replace quotation marks with " or anything like that. The plugin takes care of that, and preserves the original spacing.
The plugin has colorization support for several of programming languages, and it’s possible to add support if needed. The output is fully themeable via basic CSS.
All you have to do to invoke the plugin is surround your code in quick tags for the appropriate language, and you get something like this:
<?php echo "Here's some code"; ?>;