So, I had the exact same problem as Tim Heuer (New hard drive means re-install everything). 150GB drive and bought a nice 320GB 7200RPM with shock protection. I found the easiest way to get myself up and running was to use Win7's backup/restore feature. I backed up my drive to my home server (which creates a WIM, FWIW) and restored my new drive from my home server booting with Win7 PXE boot and restore. It took a while to backup and restore all of that, but it all worked out ok.

The gotchas...

I had bitlocker enabled (per company policy) and that obviously did not help with my disk partitioning because the 300MB partition was in the middle of my disk, so I couldn't just expand the disk partition for C:\. I had to disable and remove bitlocker and delete the partition. I also had to use BCDBOOT and point it to C:\Windows so it would automatically create my new boot config on C (since I purged it on the secondary drive)--if you fail to remember this part, you can do it using the PXE boot command prompt. I created another partition (for my boot to VHD drives) and re-enabled bitlocker. Then, reboot to validate everything went okay