I don't understand those for a 1mb connection! The downstream speeds look exceptional to my untrained eye!
These are my results for 1mb connection with Pipex:-
Downstream 905 Kbps (113.1 KB/sec) 977 Kbps (inc. overheads)
Upstream 243 Kbps (30.4 KB/sec) 262 Kbps (inc. overheads).
Try testing with somebody else such as click here (I just got 867 Kbps downstream with them, which is what I would expect from a 1mbs connection).