MORE children will be sent to the school of their choice when a multi-million dollar computer system comes on line, assistant director of education Hsu Show-hoo said yesterday. But it will be at least two years before the revised Secondary School Places Allocation system is running, and even then, thousands of children may have to accept places at schools that were not top of their list. More than 86,000 Primary Six pupils will find out today which schools they have been allocated by the Education Department computer. While 48 per cent will go to their first choice, nearly three out of 10 students will discover they have not been accepted by any of their top three schools. Some will find they have been rejected by the first 20 schools on their list. Mr Hsu said the proportion of students being accepted by one of their top three choices had been rising steadily over the past few years, partly through the Education Department reorganising school districts and also through parents becoming more realistic and not trying to send their less academically able children to top-flight schools. Complaints from parents about the school allocated to their child had also been decreasing. ''We will expect further improvements when we get the new computer system in 1995, which will speed up our work,'' Mr Hsu said. But the random allocation of priority to students in the same academic band will continue. Under the system where the computer randomly selects which students will get their first choice, the highest-achieving child in a school may not be allocated to any of his or her top three choices. ''The allocating system is absolutely fair.''