Why would you buy new Windows 7? You own the license which came with it for the life of the laptop. You can run Factory Recovery from its partition using the hotkey given at boot for Recovery, or clean reinstall as often as you wish.
Clean reinstall using the Product Key on COA sticker on bottom, following these steps to get a perfect reinstall: Reinstalling Windows 7
If you like the current partitioning then leave it. However if Recovery Partition doesn't work anyway, or you want a clean slate, then follow the steps to delete partitions during install and repartition as desired, or just delete them all and click next and Windows 7 will partition and format one large install partition for you.
Save the Product Key you bought separately to use on another machine so you don't waste the $100+ value of the one which came with the machine and you own for it's life. You can use the installer for this clean reinstall - just follow the steps given.