LGW2243T & Geforce 5500

Hi all, I know that I am new to the community so I want to say thanks in advance for any advice given.
Now on to my issue. I just recently bought a new widescreen monitor to go with my desktop so that I can watch movies and have it be low profile. However the lcd monitor i got is a LG W2243T (full spec's [url=http://www.lge.com/us/computer-products/monitors/LG-lcd-monitor-W2243T-PF.jsp][/url], and i'm running on a Geforce 5500 (yes i know it's fairly old). When I connect it by dvi cable and goto full 1920 x 1080 resolution (which my monitor supports) half of the screen is off, now I can take my mouse and "scroll" over to the stuff missing just fine, cannot access any controls via graphics card or onboard the monitor to adjust the screen size. But when I connect via VGA cable and go to full resolution everything shows up on the screen. I have the current drivers for my card. So I guess what i'm asking is does anyone have any ideas what is my problem when I connect through dvi? is my card is just to old to support this? Thanks again
On a side note I am getting me a new card eventually.

John

Well i do play some online games, but the main problem that is going to limit me is the fact that at this moment I have a mobo that only supports AGP (i know i'm sorta ancient) So i was thinking of going with either a 7600 or a 7800 agp, but how will i know if those cards will support full resolution while connected by DVI. Thanks again