Display and sound problem.

hello.
i hav been using xfx gts 250 for 8 months and i was using dvi cable with it.i hav a view sonic 22" moniter and it is full hd 1080p. so by using dvi cable i was having 1920x1080 res.

i thought i should replace my dvi cable with hdmi cable so i bought hdmi cable yesterday and as u know gts 250 does not have a hdmi slot so i used dvi-hdmi converter and then attached hdmi cable to its one end and its other end into the hdmi slot in my moniter. but when i started my comp. the res. was on 1980x1080 but the screen was stretched i mean the task bar was moved downwards and more than half of start button was not visible and my comp icon also moved into the side of screen and half of it was into the frame of screen.then i reinstalled the moniter driver and xfx graphic card driver but the position was same.

Tell me how to set my moniter to 1080p res thats fits the screen..

also there was another problem there was no sound coming out from moniter speakers. i installed my moniter SRS HD driver and also installed REALTEK HD SOUND drivers but there was no sound.

tell me how i can fix this problem?

if this whole problem is with the setting in device manager then guide me how i can change them to get sound and 1080p res.also tell me if i have to change any nvidia prop. to get 1980x1080p by using hdmi cable.

keep in mind that im using windows xp sp2 and also tell me that if i hav to change my windows for getting 1080p res and sound by using hdmi cable.