Popup search window

I'm looking for the simplest way of popping a itemid search window on top of my web site page by click a button to look up values for a field. I've got a web page for users to update item details, users need to be able to choose an item by searching for item name in a popup.

So - the popup would have a textbox and a gridview with results; clicking the "search" button in a result would populate the itemid, item name on the calling form.

What's the simplest way to achieve this?

Thanks in advance