Just thought I'd post some quick notes on doing a Windows 7 reinstall on my Lenovo W520. I'll go over some useful tools and some frustrating problems I encountered and how to avoid them.
First off, useful tools:
Start out by running Advanced Tokens Manager to backup your currently activated licenses for Windows 7 and Office. Make sure you copy this off of your computer onto a USB stick (or if you have two hard drives in your W520 like me you can just move it onto the other hard drive.
Next make sure you have no data on your Windows installation partition. Make sure you check not only your My Documents, Pictures, etc. but application settings such as FTP client's saved logon information, save games which tend to be in stupid locations, and internet browser settings (use Firefox or Chrome's sync features).
Prepare your installation media, for me this meant making a spare USB stick bootable and extracting the Windows 7 AIO ISO onto it. It also doesn't hurt at this stage to download the latest drives from support.lenovo.com and extract them onto a USB 2 stick (make sure you extract them, they come as self extracting EXEs which Windows cannot use to find drivers).
Put the USB stick in one of the USB 2 ports (the eSATA+USB combo or the always on USB) and reboot the computer. Press the blue ThinkVantage button and choose to boot from the USB stick.
When the message appears, press any key to start the installer.
Choose the correct edition of Windows to install and make sure you select Clean install. Windows should see your existing hard drive(s) as it appears to be able to use the drivers on the existing hard drive (if you've already erased your partition you might have to select the Intel storage driver from a USB stick). Once I've selected the correct hard drive I like to delete all the partitions off of it and let Windows recreate them from scratch. You may want to keep the existing Lenovo recovery partition but I had already removed mine.
At this point, you're ready to proceed with the install. Let the Windows installer copy the files and then fill out the information after the reboot. Note: You don't have to enter a license key! Just leave it blank and let Advanced Tokens Manager handle it later.
Once you've got to a Windows desktop for the first time make sure you install a few key Lenovo drivers before doing any Windows Update.
First off install the Intel wired network drivers followed by the Lenovo display drivers. The Lenovo display drivers must be installed first or Windows Update may install an Intel video driver which will cause a BSOD reboot loop. Once the Lenovo display driver has been installed you should be able to download the rest of the drivers from support.lenovo.com and run Windows Update as you please. If you plan on doing any gaming make sure you get the latest NVIDIA Verde driver off nvidia.com, it will be fully compatible with the Optimus switching.
Once everything is updated go ahead and restore your backed up Windows and Office activations using Advanced Tokens Manager