Loading speeds of media over network


Can anyone comment on the best method to optimize loading speeds of video media over a network connection to the WDTV live?

With media on a USB stick or drive physically attached to the WDTV via a USB port, a ~350MB .avi file will load up and start playing in 5-10s.

However, over a wireless connection (either using a USB dongle or ethernet via a router configured as a wireless bridge), to my win7 pc (where the media is stored)  the same file takes between 1-2 min to load and start playing.  To my mind, this is an awfully long time! This is regardless of whether the file is being accessed via network shares or a media server connection.

I assume a direct wired ethernet connection might load somewhere between the two, but this is not an option for me.

Does anyone have any tips on how to optimise the load speed over a wireless connection?  Is the bottleneck the wrireless connection or is it at the win7 end?