Though it may not be your intent this thread has the air of a lurking forum spammer. I suggest you take down the link to the site where one has to pay for RSS feed assistance. Posting such links usually violates WW TOS.
XML code won't show in most browsers. IE will let you view it with the XML parser installed but it will show in it's native XML format. If you meant that you pasted in code that used RSS/RDF then that's a different story. XML code will look something like
<headline> <title>Today's Top Story #1</title> <byline>Roger Dodger</byline> </headline> <headline> <title>Today's Top Story #2</title> <byline>Melissa McGrath</byline> </headline>
In order to incorporate the content into your web page you'll need to run it through a parser of somesort. You can build one or download one.
If, however, you've got code that makes a call to the feed source website then you could have one of two things going on. The code/feed could be broken or you are getting data returned to you but in XML format.
Also, you noted that you got the code from someone else. If the code was given in exchange for payment there may be an IP checker on the feed. In other words, they know who paid for the feed and will only let requests for their data through if the IP matches what they have on record.