Is it wrong to include parenthesis when you do this? As the function I am coding could really do with the parenthesis being there.

Would something like the following be invalid?

image.onmouseover = myFunction (myVariable[i]);

I think its that part of my code that is preventing my script from functioning properly anyway. Although no errors show up in the error console?

There doesn't look to be anything wrong with that. Any variable that returns a value can be used in the place of any string or number, as long as you are careful about the distinction between addition (+) and concatenation (+).

It does looks wrong to me...
What you should give here, is just the name of the function to be used. When that function is called, it's like an "eval".
The event can fire synchronously, but it could by asynchronous too. In the last case, the value of myVariable can be different than the one in your page.

You have to handle that into the function itself.
And remember that a function in javascript can receive an parameter, even if it's not declared.
In the case of an event, you will receive a "this" variable in your function that will be related to the element that have triggered the event.
http://developer.mozilla.org/en/docs...in_the_handler

So, the proper way (if I want to be extrem) would even be:
http://developer.mozilla.org/en/docs...dEventListener

try{
  //for anything except IE
  image.addEventListener('mouseover',myFunction,false);
}
catch e{
  //for IE
  image.attachEvent('onmouseover',myFunction);
}

function myFunction(){
  var myVariable=this.some_property.value;
  alert myVariable;
}

or:

image.onmouseover=myFunction;

function myFunction(){
  var myVariable=this.some_property.value;
  alert myVariable;
}

image.onmouseover = function() {myFunction (myVariable[i]);};

Thanks a lot for the tips! To anyone who is interested, I sorted it with the following

// display the name of the project on thumb hover

function thumbChange ()    
    {
        // set pWebsite equal to image title on hover
        switch (this.parentNode.parentNode.parentNode.id)
            {
                case 'portThumbWebsite':
                paragraph = document.getElementById ('pWebsite');
                break;
                
                case 'portThumbGraphic':
                paragraph = document.getElementById ('pGraphic');
                break;
            }
        
        paragraph.firstChild.nodeValue = this.title;
    }
    
function thumbAttr (portThumb)
    {
        img = document.getElementById (portThumb).getElementsByTagName ('img');
        
        for (i = 0; i < img.length; i ++) 
            {
                img[i].onmouseover = thumbChange;
            }
    }

Argggh... ur both right... I wasn't paying attention this time...