I don't recall being able to change teh PC version resolution above. Much of the artwork is only at that resolution and raising the graphics would introduce some wonky art. Though you could always try a hex-edit to a larger res. Info on how do do that can be found
HERE
But I recently (well, over a year ago) ran the PSX version through ePSXe - a very nice Playstation emulator - and it did a very fine job at letting me play at 1600x1200, and I thin kit looked far better than the PC version. I assume it'll work on the PS2 emulator as well, and if it does, it'll surely look even better.