I suggest actually resizing the thumbnail images. Don't just edit the CSS or HTML to make it change width/height because even if you specify the width/height it will take a long time to load a specified 125 x 125 pixel image if the original image is 1600 x 1600 pixels because it WILL actually be loading the 1600X1600 image. It needs to be its own image to be a quick-loading thumbnail. When I build websites I usually build an image database and have thumbnails of each image as well as full size; those being separate images altogether. Make sense?
Some people won't notice the loading..but those on a low-mid range DSL will.