Desktop wallpaper problem

[Skidz]

This'll sound like a simple problem, but I can't figure it out for the life of me... don't even know what to type into google to do my own research.

I have an image file, dimensions are 1280 x 800 (same as screen resolution), and every time I try to make it my wallpaper, the quality goes to shit. It looks like a horrible quality file, like maybe windows is converting it to some other format (btw, I've tried both .bmp and .png versions of the same file).

I've seen/had HQ wallpapers before and they look amazing. What am I doing wrong?

[Icari]

do you have windows "stretching" the picture to fit the desktop?

[Skidz]

do you have windows "stretching" the picture to fit the desktop?

nope, the picture dimensions are same as my resolution (1280 x 800). Nothing looks stretched, just seems like it converts it to a shitty jpeg file or something.