You mention that you are developing for the web, php, etc. It doesn't matter much whether you use a Mac or Windows in terms of what you can do, but there is a definite down side risk to using Windows, especially if you use IE. There is a risk your customers cannot see you stuff and you never find out about it because you haven't viewed the pages on their browser and platform.
If things look fine in IE, there is a great risk they won't look right on other browsers or on other platforms. If things look right in Firefox or Chrome, there is a much better chance the will look fine in IE. The fact you have chosen php over asp means you aren't choosing to depend on Windows based things. This is a good choice. Remember php is really a server side language. Your end users never see the php code. They see html that results from the execution of the php code. I don't know if IIS will properly serve PHP, but I doubt it. And even if it does, it's a non standard MS-ized version along the lines of "embrace, etend, extinguish" that MS has tried on almost every web standard beginning with html itself.
I use the Unix console all the time for web development. Some hosting companies will sell you hosting that includes a shell account. This allows you to download and install your own php add ons like forums, wordpress, drupal and the like. You can use the Unix console to extract the archives (typically tgz files) and issue commands to configure your mysql server, etc. So yes the Unix console can be very useful, but it is far from necessary. Many hosting providers will provide you a way to configure everything from a browser. It's just less flexible than the console. There are console apps on Windows that will allow you to ssh in to the Linux box that is serving up your pages but I prefer the terminal on OS X. Since OS X is Unix underneath, you can run Apache and PHP and so forth right on your Mac for testing.
If money is a problem, consider a windows box and a linux box. To me this is what OS X gives me. It gives me a graphical OS where I don't have to futz around in the terminal for things and it gives me a Unix OS I can (carefully) tinker with to my heart's content. But if money is a problem, a low end windows box and a low end Linux box might wind up costing less than a Mac. I should mention that you get what you pay for. Given the choice, I would never go for a Windows box for php development, but I want to be fair and mention that it could save you money if money is an overriding concern. Bear in mind that total cost of ownership could be quite a bit more on the Windows but that's an argument for another thread. Let's just treat the costs as if they were close to equal and say the OS X box is preferable for the reasons I've mentioned above.
I'm just learning programing and in future I would like to make big services 
