I use a static ip on my desktop because I've hosted tf2 games and torrented from that box. My ssh/cvs/print server also has a static ip because it needs to be found in the one spot each time.
The static ip is for when a machine needs to be address by something by ip address. If you have other machines on the network that you share files with, you are probably using the netbios name, which gets resolved to an ip so it doesn't really matter if it is static or not.
Each uni is different, when I was at swinburne, we had a cisco client that created a virtual network adapter which had its own ip allocation scheme so didn't matter what my network ip address was.
That was for wireless.
For jumping straight onto the wire, I had to remove any static ip address.
If switching becomes a pain (and you still want to host stuff from that box), you can see if you can reserve ip address from your modem/router. I can set mine up so that certain mac addresses only get certain ip addresses.