There are many editors for Windows to choose from. My favorite one is TeXnicCenter and I used along with MiKteX. Both are open source and there are fun to use. Latex packages can be easily installed/updated through the “Package Manager” tool which automatically gets installed with MiKteX. Version 2 Beta 1 is a stable version and has been released on November 3rd.
For Linux, I use Kyle. The interface is somehow similar to Kate text editor. I’v tried many but I think Kyle is the most complete one.