Default drivers are available through Windows update, and 7 will automatically download and install what it determines is appropriate and available. check Device Manager - If there are no warning flags, I'd leave it alone unless there were a specific issue you are trying to address.
Regarding your Video Card: ATI have up to date Windows 7 drivers available at http://game.amd.com
Regarding your Sound Card - Go to Creative and see if they have a Vista driver for it. Be advised that Creative "End of Life'd" a large number of products when Vista was released, so you may not be able to obtain a new/working driver for 7. The solution is to replace the old sound card: Preferably with one from a *Reputable* manufacturer.