There is no doubt that Malbec is the grape on which Argentina's international reputation as a wine producing nation is founded. It is a difficult grape to which the climate and conditions around Mendoza are arguably ideally suited. It is also a grape which no other country in the world cultivates to anything like the same degree - and certainly not for production of single grape varietal wines.
Another varietal used in Argentina is Cabernet Sauvignon which fares best in warmer climates, and benefits from a long ripening season. In Argentina Cabernet Sauvignon is usually picked towards the end of the harvest, in late March.

While white grapes are grown - Torrontes and Chardonnay in particular - Argentina is, predominantly, a red wine-producing nation. The hot, dry climate is simply better suited to red grapes (although this may not be the case in the future, as growers look increasingly further south for good grape-growing land).
Chardonnay and Pinot Noir are classically used for Sparkling wines.

Torrontés is a white Argentine wine grape variety, producing fresh, aromatic wines with moderate acidity, smooth texture and mouthfeel as well as distinctive peach and apricot aromas on the nose. Three Torrontés varieties exist in Argentina: Torrontés Riojano, the most common, Torrontés Sanjuanino, and Torrontés Mendocino. It is primarily Torrontés Riojano that has received attention for the quality of its wines, and is the variety used for most Argentine wines simply labeled Torrontés.
Torrontés is grown throughout Argentina and its acreage is steadily increasing. Part of its increase in numbers comes from the increase in Argentine wine exportation where the grape has found considerable success in the United States, United Kingdom and aboard but also from a better understanding and identification of the different Torrontés varieties that allow for better accounting of plantings.
The vineyards of South America have also been invaded by Chardonnay. The vine has shown real promise. Argentina has a smaller proportion of its extensive vineyards planted to Chardonnay, but almost exact reproductions of California Chardonnay have been produced under the Catena label and investors from a host of different countries have been establishing cooler, higher vineyards such as those at Tupungato.