Ok i got a quite good knowledge of PHP and .NET (for Desktop applications not Internet).
ASP language is being deprecated. If you want to use ASP use ASP.NET and buy Microsofts Expression Web 2 which is amazing.
Both languages can do basically everything. Its a matter of what you are used too and where you find more support to fix what you need.
I agree with Webassists approach to focus on PHP as Microsoft has her own development tool available in a good price and there is no need to support ASP as its deprecated officialy. If you check most published webpages are either .php or .aspx (asp.NET)
No offence, ditch that old ASP to the garbage cun :)