Despite your problems, you did the right thing upgrading to Windows 7 now. We don’t know how easy it will be to buy that version in the near future, and anything that can help you avoid Windows 8 will probably make your life easier.
I suspect you have a driver problem–or, since you have more than one piece of unresponsive hardware–multiple driver problems. This is especially likely after upgrading from XP, because Vista drivers usually work with Windows 7.
But before we bother with drivers, let’s consider some other, easier-to-fix possibilities:
If the device is a peripheral that’s not inside your PC, make sure it’s connected and powered on. And if it is inside, or connected and powered on, make sure that Windows is set to use it.
For instance, if you’re not getting any sound, right-click the tiny speaker icon in the Notification Area and select Playback Devices, and make sure the right playback device is enabled.
If that doesn’t help, you’ll have to deal with drivers.
First, is it a brand-name PC? And if so, did the device that isn’t working come as part of the computer? To clarify that second question, the optical drive and graphics card are part of the computer; the printer is not. And if you’ve upgraded the graphics card after buying the computer, the one you have didn’t come with the PC.
If you answered “Yes” to both of those questions, visit the PC manufacturer’s web site. Click the Support link, and find the page for drivers and/or downloads for your specific model number. There you should find the current Windows 7 drivers.
But if it’s a home-built or specially-build computer, or if the device didn’t come as part of the PC, you’ll have to look elsewhere. Try the device’s manufacturer’s site, or search for the make and model number, plus the word drivers.
However you get the drivers, make sure they’re for the device you actually have, and read the readme file very carefully before closing all of your applications and running the downloaded program.