Machine Spec: Intel Celeron 2.66GHz - 512MB RAM and only a 128mb V/card.

The textures do not create the rocks, no. They are similar to Vue's ecosystem stones(without the paint option) and are added as surface layers. Initialy, they will cover the entire surface of your planet, you just set the stone size, density spacing etc. for the whole layer. 
To stop them appearing across the whole planet's surface you can use a distribution shader or a mask to specify where they will appear.

This scene has 4 seperate fakestones layers and you will texture them afterwards. To begin with they are completely smooth and monotone grey. Powerfractal shaders are the best way, I find, to texture your rocks as PF shaders have an infinite level of scale detail.
The stones' colour in my image above is coming from a blend of 6 seperate PF shaders(without displacement) and 1 reflective shader, the texture is from another PF shader with displacement enabled, the scaling range for this displacement PF shader are:
Feature scale = 5cm.
Lead in(largest) scale = 30cm.
Smallest scale = 1mm.

ANY values can be set for scale giving an infinite range to play with, rather than the usual uniform bump mapping through image maps.