You can store the image locally (the faster option) or put it on a network server. When the image is created, you can import your new custom .wim file into WDS as an OS image. I strongly recommend that you put it in an ImageGroup, so you don't end up with huge WDS file sizes. (ImageGroups help WDS store only the bits needed by saving only the differences in each subsequent .wim, much like how a differential backup works.)
Before you deploy Windows 7, you also need to add your drivers to WDS. You can set up groups of drivers for various manufacturers or types of BIOS, among other filters. When you're ready, do a PXE network boot of your client; the client should get an IP address from a DHCP server. If there is only one WinPE on the WDS server, that WinPE will boot; if you have multiple WinPEs, you'll see a list to choose from. Select your OS image and answer a few deployment questions. After about 30 minutes (the actual time depends on your network), you will have set up a Windows 7 PC. Repeat the client part of the installation for each PC.
Microsoft Deployment Toolkit. This tool runs on WAIK, providing friendly wizards that ask a few questions to do all the setup needed to deploy the complete Windows 7 OS, your applications, packages (such as security patches and language packs), and drivers.
To deploy an OS image from MDT you add the OS, applications, and drivers to MDT's Deployment Workbench. Then create a task sequence. You can add all kinds of tasks to your task sequence -- even PowerShell 2.0 scripts -- by opening the properties of your newly created task sequence and clicking the Add button.
Over time, you will have multiple OS images to deploy via MDT. You determine the OS, apps, and drivers based on the task sequence.
System Center Configuration Manager. SCCM is the only Microsoft tool that lets you remotely and automatically install an OS. What you need to set up are the distribution points that contain the OS images, including applications, and drivers. Because of the amount of data sent through the network to each PC, you'll want a lot of bandwidth available and fairly short hops between the client PCs and the distribution points assigned to them.
The System Center Configuration Manager
In SCCM, you create installation task sequences by selecting the Task Sequences node in the Computer Management/Operating System Deployment node and choose Create Microsoft Deployment Toolkit Task Sequence from the Actions menu. Instruct the wizard to create a new boot-image package, MDT files package, SCCM Configuration Manager (ConfigMgr) client package, User State Migration Tool package, and Settings package. Send all the packages to the distribution points and advertise them to a collection.