Nice computer.
To help try to clear things up a bit regarding the articulation page:
Most of the basic articulations are stardard bowings: everything from staccato to detache, sustains and the like (as you know). Unlike some libraries, VSL features several different types of connected bowstrokes: legato, marcato, etc. There are six of them in chamber strings. Most of these are in the extended library portion of the library, not the standard portion, though the most critical one, legato, is in the standard library (VSL's legatos are very, very good).
There are also several performance repetitions. While the performance interval bowings include transitions between different notes, the performance repetitions are round robin samples where a different sample is triggered when the same note is repeated: very important in avoiding what is called the "machine gun" effect with repeated notes. The critical ones are included in the standard library, while the ones in the extended library are also important.
The fast repetitions are something else yet again. These are of use if playing in parts via a keyboard. If you trigger the note once, depending on how you play the note, up to nine repetitions will sound (think of it in terms of writing 8 consecutive 16th notes on the same pitch, and hitting the keyboard key once).
One of the other important aspects of the extended chamber strings library (and the other extended libraries as well) are the many different types of crescendo and decrescendo samples.
As for purchasing libraries, one first has to purchase the standard library. While you can buy a standard library alone, you must have the corresponding standard library in order to purchase the extended library (or be buying it at the same time, of course).
Finally, depending on how far into the world of VSL you intend to get, look at purchasing a bundle if you can afford one over purchasing individual libraries. The discounts for the various bundles are significant. Depending on needs/budget, doing so may or may not be possible.
Anyway, hope that clears things up a bit for you.