I'm suffering from very very poor transfer speeds of around 70-90KB/s via Powerline adapters between my macbook and Acer Revo Ubuntu machine running 10.4. This is roughly the same as the wirless speeds I'm getting which ar around 40-60 KB/s.

My current network setup is Netgear Wifi router (acting as DHCP server) with a Powerline plug RJ45 cable going into it. Then on my macbook I also have a Powerline adapter with an RJ45 lan plug going into and the same for the Acer Revo—it too has it's own Powerline LAN adapter plug.

They're all assigned IPs in the same subnet range with the Netgear router is handing out IPs.

I've tested the speed of the network first by creating a 1GB file on my macbook and using SCP to transfer the file.

Code:
big-file.bin                                                                                                                                                               0% 4176KB  94.4KB/s - stalled -^big-file.bin                                                                                                                                                               0% 4176KB  68.8KB/s - stalled -^
The Powerline adapters are rated 1000 Mbps.

Any ideas what might be causing such poor data transfer rates.