[Shamun]

In my sig, theres a link for installing highslide.

What you can do is this:
1) Use highslide single.
2) In the product.tpl file, move the detailed images from the bottom of the file to under the product_thumb.tpl include. That will put them under it.
3) In the admin section, you can set how many go across ("Number of detailed image thumbnails that must fit into the width of the thumbnail area (1-6)")