Delegates at the Cardiff conference called on the Government to spell out how it is to finance the National Grid for Learning.
Cash for the initiative, intended to improve computing in schools and connect them all to the Internet, is only guaranteed until 2002.
Jack Hatch, head of St Bede's CofE primary in Bolton, said schools needed to know that funds would be available in future if they were to make significant investments in equipment, networks and faster Internet access.
Another headhighlighted the inconsistencies of the Lottery-funded training programme for teachers in information and communications technology. He said that teachers had to train in their own time, as there was no money for supply cover, and that they were effectively required to buy their own computers.
"How many ministers have to buy their own laptops to do their jobs?" he asked.
Heads also reaffirmed their support for special schools. Speakers said that, without special schools, raising standards in mainstream schools would be much more difficult.
John Peck, head of Peafield Lane primary in Nottinghamshire, warned delegates to be wary of local authority attempts to include more pupils with special needs in mainstream schools.
He said Nottinghamshire, which already has just 0.5 per cent of pupils in special schools, compared with a national average of 1.2 per cent, wanted to include all statemented pupils in the mainstream.
Another supporter of the motion supporting the development of special schools, which was carried, said including special needs pupils in mainstream schools was simply an attempt to save money.