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This machine was originally released by Aldi in late 2004 and the Q6600 was first available from Amazon in February 2007.
Without knowing exactly what sort of motherboard, brand and model is in the Medion, we cannot say whether it'll be worth doing as it may need what's called a BIOS update to recognise the Q6600.
A spot of research turns up that your Medion uses an MSI 9701 board, which is not an official MSI board and therefore is a unique board for Medion. Any BIOS update that would be needed would need to come from them and not MSI. Since Medion PCs are sold in Aldi and Somerfield supermarkets in the UK pretty much on a "once they're gone they're gone" basis, finding support for them afterwards can be difficult.