My colleague discovered this great tool for browsing and editing of XML files. It's called XML Marker. It is free and easy to use but it has a lot of nice features. I use XML infrequently so I can't justify buying something like XMLSpy. XML Marker fits my needs just fine. I tried and was very disappointed with the free version of XMLSpy, the same colleague called it “a colorized Notepad with built-in nagware”.
I am also open to suggestions for other tools that do more for the same price, please post them if you know any.