The high-tech sector, which employs some 50,000, is crucial to the economic boom.
Attracted by IDA Ireland incentives and an ample supply of highly qualified workers, firms such as Gateway flocked to the Republic in the 1990s.
In an industry dominated by US giants, their growth was fuelled by spiralling US demand and big investments encouraged by high economic optimism.
Almost all the industry's leading players have established Irish operations. Groups such as Intel, IBM, Microsoft, Dell, Apple Computer, Hewlett-Packard, Motorola, Compaq and Xerox are included.
As well as employing thousands of Irish workers, such groups boost the domestic economy through their dependence on local sub-suppliers and services. In addition, high-skilled jobs are well paid and prosperity fosters yet more growth as workers spend on housing, food, clothes, entertainment, leisure, cars, education and holidays.
Such factors fed into the speedy growth - Europe's fastest - which characterised the Republic's performance in the late 1990s.
Once an economic laggard, with emigration the natural result of high unemployment, the State now boasts virtual full employment.
It was indeed ironic that the State training and jobs agency, FAS, last year embarked on a worldwide search for workers to fill jobs in Ireland. That programme has been suspended.
With a slowdown in the US economy now well under way, and the confidence of investors in the tech boom diminished, Gateway is not alone in embarking on a fundamental reappraisal.
Among those which have scaled back their Irish operations are Intel, Dell, Xerox and Motorola.
It is the very size of the high-tech sector which now increases the Republic's vulnerability.
