The railway company that connects Villazón with Oruro (via Tupiza, Uyuni and Río Mulatos) is modern and well-equipped, as you may have guessed from looking at the above photos. Unfortunately, some of the older travel guide books still give old information about passenger trains in Bolivia being either not reliable or even non-existant. That kind of info is outdated and NOT TRUE. The on-line version of Lonely Planet is also sadly inadequate in this respect. The outdated stories of unreliable railways in Bolivia stem from the pre-1995 era, when the railways where owned by the state (ENFE). In 1995 the railways were privatized and splitted in FCA (Andes region) and FCO (oriental region, from Santa Cruz to Brazil and Argentina).
The truth is that nowadays railway passenger transport in the Andes region of Bolivia is handled by one major Chilean company called La Empresa Ferroviaria Andina S.A. (FCA). They have to lines: Expreso del Sur and Wara Wara del Sur. They connect Villazón, at the border with Argentina, with Oruro about 850 km / 530 mls). Both lines have modern trains, equipped with everything you need for comfortable long-distance travelling. The seats are adjustable, there's video and music, heating and a restaurant service. Both Expreso del Sur and Wara Wara have three classes, yet Expreso is more luxurous and faster than Wara. Even in economy class, you'll have a reserved seat and there's a waiter who serves pollo. At night they show two films in a row. These videos are mostly secondrate North-American fighting movies or comedies, but however corny the movies might be, you'll still bound to smile at the enthusiasm of the locals, who cheer and laugh and explain every joke to their neighbours. It's quite a funny experience. Most films are in English with Spanish subtitles, so it's also a great opportunity to learn some Spanish (this is how I picked up my knowledge of Spanish four letter words - which have more letters in castellano, but you know what I mean). The conductor constantly makes his rounds, also at night, which makes it a pretty safe place. The majority of your fellow travellers will probably be tourists, more so in the more expensive classes.
Taking the train is a pretty fast way to get from Tupiza to La Paz. For instance, if you take the 6.20 p.m. at Saturday, you'll be in La Paz the next morning at around 10.00 a.m. In Oruro you'll have to take a taxi from the train station to the bus terminal. The bus from Oruro makes for a fast connection with La Paz, using an asphalted road without corners on the Altiplano. Big chance you'll already start to miss Tupiza and its lovely climate as soon as you hit the cold Altiplano!