Why do you think your only option is to buy another Win7? You own a copy of Win7 on that computer for life. They didn't provide you with a clean copy Installation DVD because the manufacturers lards consumer installations with sponsored bloatware to turn a profit, and having a DVD makes it too easy to clean reinstall without the bloatware or useless factory utilities which have better versions built into Win7.

This is why many tech enthusiasts find a Win7 installation DVD for their version to do their clean reinstall, or Repair Install. From your description i would wipe the HD and clean reinstall following these steps to get a purrfect reinstall of factory OEM: re-install windows 7