IDE for XSLT stylesheets
Editors worth checking out:
- Visual Studio
- Altova's StyleVision/XMLSpy
- Oxygen
- StylusStudio
All have their specific advantages, so just check them out. If you already have Visual Studio, I'd suggest you just getting started with this one.
My recommendation is XMLSpy, but isn't free - http://www.altova.com/products/xmlspy/xmlspy.html
If you looking for free, you can try NetBeans - http://www.netbeans.org/