The Russian invasion force in South Ossetia was 20,000, including Chechen goons and local militias, with the Russians providing a division for the invasion. The Russian units were combat veterans and air power was the decisive weapon against the Georgian army:
Despite several years of training under the supervision of Israeli and American combat veterans, the Georgians were still not as effective as the Russians (who have been fighting in Chechnya for over a decade). Although the Georgian anti-aircraft units brought down some Russian jets, the Russians basically ruled the skies and used that to constantly pick apart Georgian units. It was Russian air power the prevented the Georgians from mounting an effective defense.
Western training is only so good if the enemy has aerial supremacy. Patriots and Stingers would be a nice addition to the Georgian arsenal, I should think. Also, reading another site shows that the Georgian military was poorly deployed before the war started to defend their capital had the Russians marched on Tbilisi.
The Russians executed their invasion well, though I think they blew it by holding back from taking Tbilisi. Now the Georgians know what to expect and can rearm and reorient. And unlike our Kosovo War, where our threat of invasion actually got us a win over Serbia after the aerial campaign ended, leading to a pro-Western Serbia and the removal of Milosevic, Russia's air-power enabled road march into Georgia is leaving the Georgian government intact and hating Russia all the more.
