Slow transfer to Xbox360 ?

Son tried the 32 bit of Home Premium and it was streaming fine to his
XBox360 - status bar on 360 showing around 9. He decided to go 64 bit
( I've got his 32 bit as he never activated it) and now he's only
getting a status bar of around 2 and the picture is very jerky and
blocky.

Anyone got any ideas as to why this would happen? He can still
download at well over 200Kb so I'm guessing this isn't a network
related problem?



cheers,
Len