I am wanting to use a 'hoverover' link for the below two images. I can do this with text just struggling with images. I am new to CSS, so any help is greatly appreciated.

Here are the two image locations:

http://servernoc.net/homeblk.png
http://servernoc.net/hometrans.png

Obviously I am wanting the black image to hover the transparent one. I understand that you can hoverwith a plain black background (did not realise this so created it with text also, not a problem though I will modify BG image after).

Kind regards,