Who makes the most reliable computers? Lenovo, closely followed by Apple, if you believe online service and support company Rescuecom's latest reliability audit, derived from more than 20,000 calls made by the firm's customers during the second quarter this year.

Rescuecom assigned a reliability rating to computer vendors. Lenovo, in its guise as provider of IBM desktops and notebooks, scored 243. Apple attained 201. Third-placed HP/Compaq scored a mere 12. Dell's rating was 4, Gateway -12 and all the rest together scored -16.

What's in a number? According to Rescuecom, the scores factor each vendor's US market share - the data's from Gartner, it said, and covered the last four years - against the number of support calls the company received for each manufacturer's products. The result is a measure of how likely it is to receive a cry of help regarding a given vendor's offering, all other factors - like the fact there are a lot more Dells out there than Macs - being equal.

The higher the score, the less likely Rescuecom reckons it will be to receive a support call concerning that vendor's products - a benchmark, it believes, for the reliability of those products.

Apple, for instance, has a quoted US market share of 4.02 per cent but accounted for only two per cent of Rescuecom support calls. Dell, on the other hand, has a US market share of 17.9 per cent, but accounted for 29.4 per cent of help requests made to Rescuecom. Of the top five vendors, only Gateway kit generated more support calls than the company's market share would suggest.

Of course, Rescuecom focuses on providing IT support to businesses, so it's customer base doesn't necessarily match the demographics of the broader computer technology user base. Apple has a lower Rescuecom support-call likelihood than its market share would suggest, but is that a sign of greater reliability, or a relative paucity of Apple users among Rescuecom's customers? And how will the big battery recalls of Q3 2006 change the scores?

Rescuecom was also quick to claim that even Gateway's reliability is "solid". It said the same of HP and Dell, claiming those vendors' product reliability was merely "potentially less so" than Apple or Lenovo. Which is a bit like saying: Lenovo machines are more reliable than Dell's. Only they might not be... ®