temporarily assign the nodes to the main polling engine (settings > manage nodes)
de-activate your polling engine license from your customer portal
install the polling engine and relevant product (npm, sam, nta, etc) related polling engine components.
activate the license on the new polling engine
once it shows up is your list of polling engines (settings > polling engines), you can delete the old polling engine and assign the nodes your temporarily assigned to the main polling engine to the new polling engine (settings > manage nodes)
if the IP address of the polling engine is going to be different, then you will need to configure your devices to send traps, syslog, netflow etc to this new IP
Is the uninstalling and reinstalling all necessary? Wouldn't I be able to just turn the server off, move it over to a different site, turn it back on and change the ip address on SolarWinds somehow?
if you are physically moving the server, it should be ok. It will show up as a different polling engine when you change the IP. so, you will still need to move the nodes from the 'old' polling engine to the 'new' polling engine.
Plus during the move none of your nodes on the "moving" polling engine will be monitored.
Moving the nodes to your main polling engine is fairly quick and easy and may save you from some surprises....