If you have original remotes to learn from, I would recommend the One For All URC-9910 with a JP1 cable.
The URC-9910 is an 8 device learning remote with a small LCD screen. It has a built in RF extender that will let you control your devices from another room, but you'll need a converter for the voltage (ie, from 240v to 110v). The JP1 cable will allow you to add upgrades for any unsupported devices, including your Windows Media Center.
I have the remote available for $33 and the JP1 cable is $15. Shipping to the UK would be $9, giving you a grand total of $57. Email me if you're interested.
Rob
http://www.hifi-remote.com