Run Time Machine again to make sure, swap out your drive, boot up to your Leopard DVD, format new drive with Disk Utility (make sure you change partition scheme GUID, and then format to Mac OS X Extended (hfs+), reinstall the OS from the disk onto new drive, then when it asks if you want to restore from a previous system chose Time Machine backup, plug in that backup, and let it fly.
If the TM backup fails for whatever reason, you'll still have the original drive that was in your MBP. You can buy a $20 2.5" SATA enclosure for it online, and use that to restore from if for some reason you have to.