I only use my 50meg for my xbox its plugged straight into modem.I also noticed that my downloads get stuck,usually around 10%.
I never noticed this snag on the 20meg connection.
I`ve spoken to the uk 50meg team about problems when using xbox but tbh they weren`t much help.( no offense meant to anybody who works there
)
My connection seems ok ,good ping and downloads.
The only thing I`ve noticed that seems to help is rebooting the modem before I turn on my xbox.