>Must I always call DLL's using
>o=createobject("GetOFile.GetOFile")

Yep, cause VFP builds COM DLLs

>Should the DLL work for other systems i.e. vb, oracle or just with foxpro.

It should work in VB, and other COM languages, like VB Script in an ASP Page for example. VC++ and C# should be able to use your COM object too.