There is a discrepancy between the information in that article and what the HRW site itself says. The figures are the same but what they represent is reported differently. The Guardian states it was told by an HRW source that "doctors at Tskhinvali hospital had provided figures that 273 wounded people had been treated there during the conflict and a total of 44 dead people had been brought to the city morgue".
However the HRW site itself says: "A doctor at Tskhinvali Regional Hospital who was on duty from the afternoon of August 7 told Human Rights Watch that between August 6 to12 the hospital treated 273 wounded... The doctor also said that 44 bodies had been brought to the hospital since the fighting began, of both military and civilians. The figure reflects only those killed in the city of Tskhinvali. But the doctor was adamant that the majority of people killed in the city had been brought to the hospital before being buried, because the city morgue was not functioning due to the lack of electricity in the city." http://www.hrw.org/english/docs/2008/08/13/russia19620.htm
Assuming the latter is the more accurate, in addition to the 44 brought to the hospital there are probably: - people killed outside of Tskhinvali - people who were not brought to the hospital (adamant or not, the doctor can't be certain there weren't any) - people who have died of their injuries since this doctor was spoken to
Agreed that these extra figures are unlikely to reach the 1500-2000 mark but, certainly, they would push it up well over 44.