Paul,
In addition to what Bonnie said you can add an existing project (old project) to your solution, that way if you make changes to the old project (in the new solution) the dll or exe from the old project will be recompiled every time you build the solution.
In the project where you want to use the old project (both in the same solution) you sill have to add a reference to the old project but you do it from the projects tab in the add reference dialog.
I usually do it this way if I know I will be making changes to the old project at the same time as I am working on the new project.

I hope this makes sense, feel free to ask if you don't understand what I am talking about.

Einar

PS. There is no such thing as a stupid question <s>

>Bonnie,
>
>Thank you for your quick reply. That is what I needed. I am going to be referencing projects from other solutions. Don't go to any trouble but if you think of this step to help with the dilemna of an old .dll I would appreciate it. I will look myself.
>
>Thanks again,
>Paul
>
>>Paul,
>>
>>The "using" statement is simply a way to implement a shortcut in your code so that you don't have to say xyzproject.MyClass, you would simply say MyClass. But, in order for one project to recognize another, there's an additional step you have to do and that is to add a reference to the xyzproject. In the IDE, in the Solution Explorer, right-click on your project and choose "Add Reference" and click on the Projects tab. All the projects from the existing Solution will be displayed in the ListView. If you want a project from another Solution, simply click the Browse button and go find the .DLL. This will copy the .DLL into your bin\debug folder. The downside to grabbing a .DLL from another Solution like this is that when that .DLL changes, you are no longer referencing the changed .DLL (because you put a copy of the old one in your project). I think there's a way to overcome this, but off the top of my head, I don't remember what needs to be done (and I can't look it up right now).
>>Someone else may know, but this should at least get you started ...
>>
>>~~Bonnie
>>
>>
>>
>>
>>>I am new to .net and visual studio .net.
>>>
>>>From within a c# file I am wanting to reference code that exists in another solution. Can I do this? I tried issuing a 'using xyzproject' statement. But the compiler doesn't like this statement.
>>>
>>>What am I doing wrong?
>>>
>>>Sorry about the stupid question...
>>>
>>>Paul