Well, in every game out there applies the simple law: "You got high-end machine, you see the game at its best". Now, this law is additive
; you have low-end computer, you have a low-experience of the game. You gain a better computer, you get a better experience of the game. Experience stands for graphic details, smooth gameplay and sound perfomance.
you have a high-end computer or a reletavely strong one, you should go in the Options>Video and click on the "auto-detect settings". This should fix everything to match your computer perfomance. Yet, in some rare cases, this might not work well, so, drag ALL the bars (apart from Gamma correction) to max; same applies for the "Advanced..." settings. Enable "Hardware cursor" and "V-Sync".
Finally, each monitor is manufactured to work best in a ratio/resolution. Mine Viewsonic VX724 for example works best for 1280x1024 resolution, <4:3 ratio. If your monitor does not work best in a specific resolution
, then the higher the resolution, the better graphics.
Hope this helps