Mr John Dillon is not generally known in Ireland but the US chief executive nonetheless has a certain notoriety here. He is the man who persuaded three of Oracle Ireland's top executives, including managing director Mr John Appleby, to join an unknown dot.com.

Sitting in Dublin's Conrad hotel and sipping a mineral water, Mr Dillon turns out to be an immaculately-dressed former US military man, who most recently led Hyperion Solutions. He speaks with careful intent, until he reaches a more passionate full throttle in discussing the company he now leads, Salesforce.com. Then, he leans forward in his armchair and his hands start punctuating his sentences.

Salesforce.com does SFA, says Mr Dillon, which stands for sales force automation. He has been warned that the abbreviation has a slightly spicier meaning in the Republic and Britain, a meaning which implies that the company does sweet nothing.

He spends the remainder of the interview fighting the ingrained Silicon Valley love affair with acronyms and corrects himself with the full phrase every time he begins to say the abbreviation.

Since its March arrival, the dot.com has succeeded in picking up about 1,000 customers for its specialised online service and has rattled formidable competitors the size of Siebel Systems and Oracle - not least because Salesforce.com, founded by former Oracle man and Siebel investor Mr Marc Benioff, has been scooping up former Oracle highfliers like Mr Appleby as well as grabbing clients from the big companies.

Software that automates a complex activity, such as the myriad operations of a company's sales team, is nothing new. But Salesforce.com's slogan, "the end of software", sums up exactly why the upstart firm worries giants like Siebel and Oracle, companies that earn their revenue by locking customers into elaborate software packages that typically need a dedicated maintenance team.

Some analysts suggest that up to 90 per cent of the total cost of ownership of these "enterprise" (or more derisively, "bloatware") software packages is simply the maintenance - updates, additions, training, inputting data and learning how to use its features.

By contrast, Salesforce.com has created a package that is accessed entirely over the Web, is maintained and kept current by Salesforce.com, and costs $50 per month per user. Mr Dillon says that makes the total cost of ownership for using Salesforce.com's service much cheaper than its big competitors' packages.

That argument has persuaded IBM to offer Salesforce.com as its sales software for small to medium businesses, while retaining Siebel's SFA software for its enterprise offerings. Salesforce has also agreed a deal with Business.com to be its sales software offering, giving the company another highly-visible platform to reach online customers.

But Mr Dillon expects Salesforce.com to start eating into the enterprise market as well, a sector currently worth about $100 billion (€114 million), according to analyst International Data Corporation.

Companies aren't happy with the packages and their complexity. Gartner Group says that of 1,300 companies it surveyed recently, 74 per cent said its enterprise packages failed to meet expectations.

"What that tells me is that people want the promise of the technology, but that the technology hasn't been adequate to deliver," says Mr Dillon. "We believe it's time to do it differently."

Thus Salesforce's "online business service" - a phrase he prefers to ASP, or application service provision which more specifically refers to software rental and outsourcing. With ASP, companies still need to tailor the large packages they rent over the Net to their own needs.

Salesforce offers a generic package that Mr Dillon believes will suit 60-80 per cent of companies and has an adequate degree of customisation and configurability - enough to allow most people to make desired changes on their own, not through their technical support division.

"Since the customer makes almost no financial commitment up front, it's virtually risk-free," says Mr Dillon. "There's no contract, no lengthy sales cycle. In other words, this disrupts everything [in the enterprise software model]."

The established companies such as Siebel, SAP and Oracle will be slow to react, he believes. "They realise there's a shift. They realise it will be difficult for them to turn."

Both Oracle and Siebel have set up their own online divisions recently, but Mr Dillon is dismissive of such big company manoeuvres. "You can't retro-fit an old product and make it work by adding an `e', an `i' or `my' in front of it" - the prefixes used by several existing software companies on their Internet-oriented software offerings.

He says Salesforce.com's next step will be to develop other elements of enterprise software so that the company can provide a complete online service, beginning with a customer relations management (or CRM) module in the next few months. "It's a wide open market, very, very big and growing," he says.

The battle for that market in the sales sector promises to be entertaining for onlookers, if only because it pitches so many former Oracle bedfellows against one another in competition.

Siebel and Salesforce.com were both founded by defectors from Oracle, and Oracle founder Mr Larry Ellison and Siebel founder Mr Tom Siebel sat on the boards of these respective spin-offs until the splinter companies won contracts over the larger company or the larger company launched a competitive division to its spin-off. Prime entertainment, Silicon Valley-style.

Europe is the next market Salesforce wants to go after, but the roll-out will be gradual: "We're doing it very quietly. Were making sure we have the cultural idiosyncrasies addressed and then we'll have a formal launch," says Mr Dillon.

Salesforce's European headquarters will be in Dublin - hence the recruitment of Mr Appleby and his colleagues from Oracle. Mr Dillon lists the usual attractions of the Republic - low corporate tax, a pro-business environment, solid infrastructure - but adds: "I didn't do it here necessarily because I thought I could do it cheaper, but because I thought I could do it better." The Irish contingent numbers 12 and will grow, he says.

Recently, an interviewer asked him what keeps him awake at night. "I'm sleeping better now than in years," he jokes. And what does he find most challenging? "Execution is really the only sustaining challenge," he says.