Scott Guthrie [Another MSFT Genius!] recently posted on how to change the default browser used in Visual Studio 2005 and Visual Web Developer 2005. This technique works for other file types as well and I've used it to help customize the tools used by Visual Studio to create/edit CSS and TEXT files. Don't get me wrong. I really like the basic CSS and text editors that come with Visual Studio but sometimes a developer just needs a little something extra such as TopStyle Pro from NewsGator Technologies and TextPad from Helios Software Solutions.
I really like TopStyle for editing CSS files since it offers "intellisense" like code completion and an excellent HTML preview for those of us that are somewhat CSS "challenged". I use TextPad for most BizTalk projects that involve flat-files since it allows me to "see" the flat-file structure (tabs, spaces and CRFLs) which the default VS text editors don't.
Each of these can be set as the default "editor" in Visual Studio by right-clicking on the file you'd like to edit in the Solution Explorer (as shown below) and then selecting "Open With..." from the pop-up menu.
In the "Open With" dialog box that opens, you can add a new editor by clicking on the "Add" button and pointing to the executable file (such as the TopStyle CSS Editor) and then by clicking the "Set as Default" button.
This is a really simple (yet powerful) way to customize Visual Studio to meet your personal development needs and style.