Alexandre,
Appreciate the suggestion, but that was not the issue... Im one of the lucky ones, with the exchange in my back yard, on the other side of my fence; say 100m maximum.
Further research showed the ADSL link between myself and iInet reports 20 mbits per second, I.e. d/loading from 'their' web or ftp server. Clearly the problem had to relate with iInet's external link.
As final proof, I setup a net speed test between myself and another iInet client in Perth city who also "had slow internet browsing". I can't renember the speed transferring data between us, but it was flying! And, remote desktop sessions between us felt no different to a local lan connection.
Certain times a day, and much more noticably, during school holidays, browsing etc boggs down to a crawl...