I also disagree tat ASP is obsolete. As Sheco pointed out the skills from writing ASP are transferable to other areas.
At the same time, the skills in writing PHP are equally transferable.
PHP does have a command-line executable that you can install (if you are allowed to install PHP on every box you want to use it on) and the language has a much larger syntax.
ASP uses VBScript (commonly) or javascript (less commonly), both of which can be used for command-line scripting in Windows without extra installations (most of the time).
PHP is generally faster then ASP when doing similar tasks. ASP can be written in a variety of languages (as ASP is the technology, not a language). Personally I have written it in VBScript, Javascript, Perl (via ActivePerl), and Python. They each havetheir tradeoffs efficiency wise, but I don't believe any reach the level of speed that PHP does (though I could be wrong as I haven't tried the newest Perl modules that are distributed with ActivePerl now).
Personally I like ASP because it has a limited syntax. The limit means I can pick up any piece of ASP and read it without having to retreat to a reference manual every three lines because a developer used a function I'm not familiar with to do something that has 16 other functions. It also means tht I could master it more easily and keep on eye on performance as I design pages becaue I already know some of the best manners for doing particular tasks, rather than having to examine a multitude of similar functions. Obviously there is a tradeoff there, but I also think that the code I write in VBScript or ASP comes out prettier than most of my PHP code. Part of this is experience with the language and part of it is just the fact that the VBScript language does have such a simple syntax that it is easily readable.
Personally if I had to pick something up from scratch today, I would likely go with PHP, for the above stated efficiency reasons. However, if the tie-in between Python and the ASP objects (response, Session, etc) had been better (and I could convince web hosts to install it) than I think that would have been my first choice.