Dell Studio 1555 - screen resolution issue

As I stated, I have a Studio 1555 bought back in 2009. I recently had a hard drive issue and had to replace it. With replacing it, I reinstalled Vista and the drivers; however, now the screen resolution only allows up to 1152x864 - which slightly stretches the screen horizontally. Before my hard drive issues, it was not stretched in the least. I'm thinking that I may not have installed the factory drivers correctly, but I'm not positive. My replacement hard drive is slower (5400 rpm as apposed to my earlier 7200 rpm), but I was told that this would have nothing to do with my resolution problem. Any thoughts? I'm an amateur photographer and graphics guy, so this resolution issue just won't fly. Any help would be greatly appreciated.