Static or Dynamic?
First, let me start off with a warning. Before you attempt any of the steps in this guide, I highly suggest that if your machine is working the way you want it to, to go ahead and write down all the information you'd need to restore it to the way it currently is. You'll often find that when messing around in the IP settings of a Windows machine, it can be difficult to make it cooperate with what you're wanting to do. Windows is very adverse to change, and as such, it's always a good idea to backup all your files and settings before making any major changes - especially those files that you need to keep your server running efficiently with your website or web application on it.
Now that we're past the disclaimer, let me also issue one final warning. Dynamic IP addresses were invented for a reason - that reason is to make your life a little easier. The dynamic addresses allow the router or networked device to quickly switch between IP addresses in the event that one particular IP address is being difficult. Just keep in mind that if you're not sure what you're doing with regards to the changing the computer to a static IP, it'd be better to leave it the way it is.
Now that I've fully said my peace, here's what you need to do:
1. Click on the Start Button and navigate over to the Control Panel
2. Once inside the Control Panel, you'll want to right click on Network Connections and navigate over to the connection you want to configure.
3. Click on the aforementioned Network Connection with the right mouse button and click on "Properties".
4. Now that you're inside the Properties screen, navigate over to the General tab (if you're on a LAN) or to the Networking tab (if you're on any other kind of network).
5. Once inside there, you'll want to click on TCP/IP and click on "properties" once again.
6. Inside the TCP/IP settings properties is where the real work begins - make sure you know all your networking information (IP settings, gateways, etc).
Side Note: To get all this information for step six, go to start -> run -> type in "CMD" (without quotes) -> type in "ipconfig /all" (without quotes).
7. Once you've got all the information, go ahead and type all that in for the Default Gateway, and the Subnet Mask (which on LAN is usually 255.255.255.0) - the IP address will be the one you want to set the computer to.
8. When the DNS server settings aren't gray anymore, you can go ahead and fill in the same default gateway as before - if you're not on a LAN, you'll want to consult the network specialist for more information.
And that's all there is to it. The one caveat I have to add to this, is that about 1 time out of 3, this procedure didn't seem to work for whatever reason on the machine I was testing. There's no real explanation that I can come up with - however, the problem seemed related to my ISP and how things were configured in the LAN, so fret not if this doesn't work for you - just make sure that your NetBIOS are on - I can't stress that enough, as that can cause several issues.