[TxMt] The dreaded Regexp question

Sorry, I know this isn't particularly on-topic (aside from the fact that I'm using Textmate!) but I'm not having luck with the search engines.

I have a bunch of HTML that needs to be converted to XHTML, notably <input type="text"> needs to be <input type="text"/> which is easy enough. Problem is, it's PHP so there are things like <input type="<?php echo $type?>"> which I'm having troubles with. So how can I create a regular expression that captures the guts of the HTML brackets, while ignoring any PHP brackets it might come across inside the HTML?

Thanks in advance.