There're some interesting threads over at SitePoint Forums:

Java or .NET -- What to Learn??
Head-to-Head: PHP vs. ASP.NET

Also, Harry Fuecks from phpPatterns() has recently written an article on XUL entitled Introducing XUL - The ‘Net’s Biggest Secret: Part 1 for SitePoint. Nice introductory article, but he does seem to make it (XUL programming) more difficult than it actually is by involving the PHP bit.