On a side note. I actually have Notepad++ open all .cs files by default. As I generally only ever open a C# file directly like that for a quick simple edit. So no reason firing up VS for a quick edit, as it's a rather large and resource heavy app. However, I almost always have VS open too. So I generally do all of my changes form there, as most people SHOULD.
Using a proper IDE is very important when working with a programming language. If you're using Notepad++/Programmers Notepad/Notepad/ect for all of your development, you are most definitely doing it wrong. A proper IDE will save you all sorts of headaches with errors, tracking down bugs, viewing source more easily (can right click most types and go directly to the definition, or even find all references) and much more. Although you benefit even more if you're working on your stuff with a properly setup solution. Using the ServUO solution and writing your new stuff from within the entire solution, you'll find it even easier.
Notepad++ is just a basic notepad, that supports syntax highlighting. There are a ton of similar programs that do the same, that are basic text editors. Such as Programmers Notepad, Sublime, hell there is even a chrome web app that does the same thing.
While I don't share Insanity's enthusiasm for VS, I use Notepad++ religiously. Most of what I'm doing though is syntax correction or minor adjustments. Running VS to correct a recurring phrase seems a bit like overkill heh
I have used VS in the past for things, so I do understand how valuable it can be, but for the most part Notepad++ is just easier to work with since it's a relatively small app.