After having read so many of the comments on this site regarding Lao & Thai and even Cambodian histories from the posters on their perspective of her or his story telling,  I want to share a well researched book that summarize the majority of our feeling ( Lao & Khmer) regarding our neighbors.  Instead of making things up as they go along like most posters tend to do, this book does a great job in capturing the feelings toward our respective neighbors Vietnam and Thailand.

Here's a concluding paragraphs from the book:

Nationalism and cultural revival in Southeast Asia: perspectives from the Centre and the Region by Harrassowitz Verlag

From the Chapter:  Lao and Khmer Perceptions of National Survival

The course of events during the first half of the nineteenth century and the accumulated experiences have shaped national consciousness in Laos and Cambodia quite differently.  The Lao had neither lost significant portions of their territory nor of their population to Vietnam but suffered in this respect from considerable losses to Thailand.  With more than 80% of the Lao people living outside the Lao nation-state.  Lao national identity had to be reinforced vis-a-vis (face-to-face with) the Thai.

Cambodia as well lost large parts of its territory permanently to Vietnam (the Mekong delta) and to Thailand (the "Forest Khmer" provinces of southern Isan).  Part of territorial loss to Thailand, however, was compensated for by gains from the Thai (Koh Kong) and the Lao (Stung Treng or Xiang Teng in Lao).  In contrast to Laos, the Cambodian heartland could be saved and the vast majority of the Khmer population remained within the present borders of the Khmer nation-state.  As the Thai rule in the "Forest Khmer" provinces did not change the ethnic composition of the region significantly, the Cambodian perceived the Vietnamese as the main challenge to their national survival.  Any significant settlement of Vietnamese in Cambodia would evoke Khmer fears of extinction.

However, these different perceptions did not prevent Lao nationalists during and after World War II from appreciating the Thai support for their anti-colonial struggle or Khmer nationalists from seeking Vietnamese support at the same time.  This was possible so long as progressive Thai and Vietnamese governments dissociated themselves from the expansionist policies of former regimes and paid attention to the anxieties of their weaker neighbours.