New wide screen monitor on a very old computer

the monitor on our very old desk top went out and I found a cheap open box wide screen LED at best buy. Only problem is it stretches everything out (American skiers look about 23 feet long)and leaves about a half inch off the right side of the screen If i put it into the more square viewing option it gets real small. and still leaves about a half inch of non-viewable information on one side so I have to move the image back and forth. the computers video card max resolution is 1024x768 and the monitor calls for 1680x 1250. Would an AGP card get me up to the resolution I need and fix the display issues. the computer is an old pentium 4 sony vio. I know it should be replaced but if I can hold off by buying a used AGP card for $10 I would prefer to.