Hi stephanie.
I hope I have understood your post and what it is that you are looking for. Please correct me if I'm wrong.
I do not have this more pics mod installed myself, but it occurs to me that you will want to keep the following in mind with pics:
You will always want the ratio between height and width to be commensurate to each other between the original picture you uploaded and the dimensions you are asking the web to produce. For example: If you have a picture that you uploaded and it's dimensions are 100x100 , and you ask the web to produce that same image at: 175x135 , your picture will definately be distorted or blurry. In the case of the above example, the height -vs- width ratio is 1 to 1. You could make it 200x200.. or 300x300 ... etc. Once you get the original dimensions, you can use your favorite image editing program to get the exact numbers you will need to plug into your programming to make them show up correctly. Most of these programs have an option to resize photos (just as a test) ... increase the size of perhaps the height, make sure that you have checked to keep the width in proportion. Use the numbers it gives you. In your particular case.. if I understand you.. with a small image at 130x160... if the height is 450... the width should be around 554 off the top of my head. (You will want the exact number from your image editor).
By the way.. you mention that you are using 130x160 for the smaller image... and the pop up image is 450. I would imagine that 450 is the height.. what is the width? Also... what is the size of the original image you uploaded. Knowing these things can help us help you.
Iceman