Here's a couple of OSX applications I couldn't live without: Coda - http://www.panic.com/coda/ SK Edit - http://www.skti.org/ I favour 'Coda' which I highly recommend–simply awesome. However 'SK Edit' has a much more sophisticated search tool, which allows you to search whole sites for specific terms within the code. For this reason I end up using both applications.
I don't know how full features these are, but I use TextWrangler for these tasks, it supports full FTP access and basically rocks. Free, too.
Do it! OSX is well worth it + you can run Windoze is you still need to For local development, I use MAMP http://www.mamp.info/en/mamp.html