Small Layer Info On Mouse Over Links : Object Or Iframe ?

I would like to display a small html file in a layer (div) when the
mouse goes over a link (<a href="small.html"
onMouseOver="showPop(small.html)").

Which tag should I use in the layer :

<div id="pop"><object data="small.html"></object></div>

OR

<div id="pop"><iframe src="small.html"></iframe></div>

Or maybe is there another solution ?
--of course the file small.html will be different for each link on the
page, that's the job of the showPop() function--
I want my site to be visible by as most browsers/platform as possible.