I've PCs, Xbox 360, Network Media Player and Smartphones connected to the BT HomeHub, how do I give every device a static IP so other device can't slow down others?

What exactly are you trying to achieve? What do you mean one device slowing others down? I presume you mean that when all your devices are accessing the internet at the same time that they all slow down?

That has nothing to do with IP addressing. It's simply that they are all trying to share a finite resource, your broadband bandwidth. It won't make any difference to that if you give all devices static IP addresses or not.

I'm not sure if it's possible with a BT HomeHub but there is a potential to allocate a minimum amount of bandwidth to a particular device.

If I go to Home Network -> Devices and select the device, I get this screen,

This is my Xbox 360,

http://www.ultraimg.com/images/nN5Fp.jpg

Should I tick Yes on "Always use this IP address"

The only benefit to doing that is if you want to connect one device on your network to another and my means of IP. Otherwise it will make mom difference.

Not entirely sure what that has to do with "slowing other devices down" as you asked in the OP?

If I tick "Always use this IP address", then each devices I've connected will use it's own IP address, this will give each of my device a little bit better connection?

I think I may know what you're driving at. But no. It will not.

Each device is issued an IP on your internal network by the router when it connects. If you check this box then every time a device connects it will be given the same internal IP as it was last time.

This is nothing to do with the external IP.

So it's best to leave it at No?

You can do what you like.

It can be useful if you want to communicate between devices on your network.

For inexperienced users DHCP is best. One avoids IP address conflicts automatically and doesn't have to lean how to avoid it manually.

And, as has been alluded to, in terms of performance, Static Addressing is no better/worse than Dynamic.

Best idea- always use DHCP. And it's only devices running servers that may need a permanent DHCP IP address reservation off the router (best way to allocate static IP). Stuff like NAS servers, print servers/network printers and the like.

Client kit can go with dynamic allocation. As most of your kit will be INITIATING connections, leave it dynamic.

With out home network I use a mixture of static and DHCP assigned IP addresses. Things like NAD drives, we have three, work better with static IP addresses because they are always in the same "place" as far as laptops and PCs are concerned, especially if you map them as Network Drives, but certainly for devices like laptops, tablets, etc, I use DHCP.