You can't have an enlarged version of one of the houses in the game cos there are no jpg files for them, but you can have a larger custom model that is a house. It won't have the same design as the normal houses though.
Btw, your sig thingy isn't working because you forgot the / in the last img box, and it's not a proper URL. It would have to have the http:// bit in it.
If you right click on someones sig, click properties and look at the URL, that's what needs to be in between the img boxes.
