I originally started using Classic ASP, then switched to PHP - that was back in 2003.

Now, having just left a company and looking for employment, I find about an equal amount of PHP and ASP.net job openings in my particular area. One caveat: the .Net seems to have a higher pay scale.

What I have is close to 5 years PHP experience, 4 of that design web apps and sites, 1.5 years Java training using official Sun curriculum and enough .Net experience I can make code changes and code simple tasks.

Still unemployed though. So you take your chances either way - depends upon the market where you live and/or work, and where you want to live and work. If the market is .Net there, you may find a .Net programmer on every corner, just like in my area there is a PHP programmer on every corner....though as we all know, some better than others. So why not diversify? Learn more than one and stand apart from the next guy in line?