in paint adjust the image like this, however in your screenres you will lose the taskbar unless you do the end option as well...
edit the image in paint and select image > attributes, under units ensure you have pixels highlighted and change the screen res on width and heigh to that off say a 17" monitor 1280x1024...
this will then adjust the size but also crop the edges regardless of the image content. the only way to compensate for this is at the first stage whilst you have the entire image selected move it up (Drag) a tad to allow the room for the crop but of course you will lose the upper edge of the image but wont suffer the text blur.
or better still photoshop it.... for best results....
long winded way around this is to alter your desktop screen res to low 800x600 or whatever you wish the image in, save the image in paint without adjusting it and the set it as you background image (desktop wallpaper) then take a screenie of that using "prt screen" open and save this in paint and it wont require any resizing, maybe a crop on the edges of you have a widesreen monitor
NOTE: lowest res (800x600) will result in large text, recommend 1280x1024, then if really really need to adjust size of image in paint but adjust to say 80x80 from 100x100 should be ok at this, text should look just fine, etc