Problem with Pulling images from last 5 threads

[lasto]

I have a hack which pulls images from the last 5 latest threads which are made in a certain section.
Now the problem is this : When someone ups a preview the preview image is lets say for example : 250kb.
Now on my last 5 which is displayed on forum home in a set box the preview images are small sizes (100x80) but their size is the size (250kb).
And because of this there is some load because 5x pics means you have to download 1.25 meg just to view the last 5 preview images on forumhome.

Does anyone know a better way to do this so the smaller images which go on forumdisplay are actually smaller in size without affecting the actual pic in the thread.