Q:

RSS or XML

I need to get data from a web site written in PHP.  My boss wants me to provide an RSS feed to get updated content.  
The problem is that I need to provide several informations (at least a dozen different field).  Is returning data as XML a better way than RSS? 

A:

RSS is a form of XML. 
If you find yourself outputting the same sorts of data as what is in the RSS specification, it definately doesn't hurt to output in the RSS spec.  That way, you can syndicate your content. 

A:

It's really going to depend on what the data is and how it's going to be consumed. 
RSS is XML, but it's XML meant to syndicate data with a consistent format (there's a pretty good overview here: http://cyber.law.harvard.edu/rss/rss.html), and that allows feed readers and other consumers to know how to process and display them.  So if your boss wants to look at this data in his or her feed reader of choice, then go for RSS. 
If the data is more varied or arbitrary, and is going to be consumed by some sort of application or other processor on the other end, then XML is probably a better solution.