Tweak graphics settings principal components

Whilst many people will tell you that a graphics card is the most important component for gaming, it is not strictly true. The truth is that the balance of components is the most important.

In your case, anything but a modest graphics card will be overkill for your system. Even if you had a top of the range graphics card, you wouldn't get much out of it, because you are severely limited by 1GB of (relatively slow) RAM.

Should you upgrade your memory, your CPU will become the limiting factor - and in certain games, the CPU will prove even more of a bottleneck than your RAM.

A single 7200rpm SATA drive isn't particularly speedy either, but you are some way off it becoming a limiting factor. Faster HDDs will enable you to load levels faster, but have far less impact on frame-rates and graphical quality.

However, in a system where all components are of a similar generation, the first component to upgrade would be your graphics card. As a rule of thumb, I might suggest you keep your components within one generation of each other.

Your PC would be regarded as obsolete, but that isn't necessarily a reason to write it off. What is does mean is that buying a gfx card one generation ahead of your current one, doubling (or perhaps even quadrupling) your RAM and upgrading your CPU by one generation would be cheaper and would yield a far greater improvement than buying a latest-gen gfx card.

I don't know about a comprehensive guide, but I have a few suggestions.

First, as background, every setting is going to be geared towards balancing two different (and diametrically opposed) optimizations--that of speed in calculation, and size in memory. For instance, your texture quality, and to a lesser extent, model quality, will have a large memory usage with relatively minimal processing imprints, whereas your physics, shadows, and reflections will be rough on the CPU/GPU but in some cases have absolutely microscopic memory footprint. I'll call this Speed vs Size.

Your Size-heavy settings are going to increase load times between levels and eat up RAM, which would slow down other processes, but we'll assume you're running SC2 by itself. Your Speed-heavy settings are going to affect your FPS the most, and also have the most wow-factor.

So with that in mind, whenever I have to turn my graphics down because I'm playing tug-of-war (I usually run on Extreme:D ) I default everything to medium and then turn texture quality to high, shaders to high, reflections off, particle effects to low, physics to low, and Model Detail to high. If you hover your mouse over each option it will detail out what it does, and you can usually tell whether it will be more of a Speed sacrifice or a Size sacrifice, and if it's not clear-cut it's a mix of the two.

I did a test to show the difference, this is a shot of a replay on ultra, and this is a shot with the above settings. I started the match with about 80 fps on ultra and about 130 on the frugal settings, and around this point (tons of marauders, roaches, marines, and carriers) I was running around 40-50 on ultra and around 60-70 on frugal. As you can see, there's not a whole lot of difference in the stills, but it was noticeable enough--you can see the lack of motion trails on the interceptors, for example, and some of the explosions weren't as spectacular.

You shouldn't have a problem with that machine, but if you do, you can try these settings as a starting point, or try setting the various Speed settings even lower. You probably won't have to put the texture or model quality lower, as in general that will just affect load times and not so much the calculations.