What you are asking will not resize images proportionaly, and the result will be ugly...try change height of an image and you'll see what I mean.
You mean resizing with Fixed Width & Fixed Height will make images ugly??
That is quite possible but in only one case. Where image will have height greater than width.
But in my case almost everyone will upload standard wallpaper which always has width greater that height.
I try uploading a wallpaper of 1280*1024 (a standard size) & the result was 1024*915 & thumbnail 133*111
Currently, with every new upload, I have to do this:
• Download that wallpaper
• Resize it
• Upload
• Delete thumbnail
• & then create thumbnail.
So if making Width & Height Fixed have a slight effect on image quality I would go for this than to do all these steps.
Or You can suggest me a better way.