We could get a new PC base unit, say the Inspiron 530 from Dell for around £400.
We could also get a new smart media center PC like the Tsunami Intel MJR2 Media Centre HTPC.
Or just get a Zalman HD160+ Home Theatre PC Case for around £160 and fit our current PC bits inside. It does need an ATX PSU.
There's also the Silverstone LC16M Silver Case for £160. It does need an ATX PSU.
The ThermalTake Bach Media Lab case is £119 from MicroDirect.co.uk, and comes with its own remote, but no PSU.