As a Microsoft Visual Studio developer I plan a side-step to the php-world for developing a moodle-module. What tools do you use? (IDE?)
I just downloaded dev-php , it looks promising
Welcome to the world of 'proper' programming languages 
This one has been discusses a 'lot'. You don't say what platform you are using but I assume its Windows. I normally use a Mac or a Linux box remotely, so I use vim (www.vim.org) or gvim the graphical version, along with ctags for finding stuff. You can get this for windows as well of course.
On the odd occasion I use a windows machine I tend to use HTML-Kit from www.chami.com, which understands PHP (and lots of other stuff) quite nicely. Most free IDEs I have tried have been dreadfully slow.
This one has been discusses a 'lot'. You don't say what platform you are using but I assume its Windows. I normally use a Mac or a Linux box remotely, so I use vim (www.vim.org) or gvim the graphical version, along with ctags for finding stuff. You can get this for windows as well of course.
On the odd occasion I use a windows machine I tend to use HTML-Kit from www.chami.com, which understands PHP (and lots of other stuff) quite nicely. Most free IDEs I have tried have been dreadfully slow.