IMO, programming is programming, but you will run into syntax differences with for loops, while loops, etc...
and there are less (in numbers) handy functions in ASP than PHP, for example, if you are used to using [man]copy[/man] or [man]move_uploaded_file[/man] in PHP, good luck using those in ASP, ASP needs a third party program to do file uploads easily, or you need to make complex code to upload files, that is just one example, but you probably get the idea
but like i said, if you know how to program, and you get the syntax down and have a book handy for the functions, you should be able to get around it after a little while