A. There are a full 2 GB of ram installed, however other devices (video card etc) have been designated a portion of the system RAM to function.
B. System has 2 separate 1 GB sticks installed to equal 1896 MB of Ram. If a single 2B stick was installed it would read correctly.
C. RAM measurements are similar to the hard drive discrepancy in that a GB definition difference exists between the manufacturer and the operating system.
D. The manufacturer rounds up to the measurement to the nearest GB for ease of sale. The Operating system reads the actual amount of the chip(s).