[gavinflud]

My first job in the development industry was working as a PHP developer for a nine month internship.

Now that I'm graduating I received several job offers, most of them involved working with PHP again. However, I received two offers from two relatively large companies, one as an ASP.Net developer and the other as a Java EE developer. The salaries for these two jobs were quite a bit higher than the others and included great benefits too.

Again, I'm only a graduate so can't really give any solid answer as to whether you're sabotaging yourself by working with ASP.Net, though I doubt you are. Most decent employers will probably be more interested in ensuring you can program rather than focusing on what specific language you've been using recently. If they know you can program, they can probably assume you'll be able to apply that knowledge to a new language.