changing image dimensions on mouseover

[sookaa]

I have a series of images that change on mouseover events in a webpage i am developing....2 out of the images however are different sizes than all of the others...they are, actually different a ratio dimension than the others (so resizing looks like utter crap)....so the way i have it now is a spacer image that is a blank gif is the orignal image, sized at 400*300, this then gets replaced as necessary with the other images when called....however, the two images that are 300*400 get stretched/resized into the 400*300 size...how can i easily get these two images to display properly...i cannot use layers, this is all table based

cheers

sookaa