I notice that under sound card in your specs you have listed Realtek High Definition Audio Driver. That would actually preclude Realtek AC97 Drivers from working. I am curious, what model computer do you have or if you built it yourself, what components does it have? It would help in troubleshooting this. If you're not sure, you can use HWInfo32 from http://www.hwinfo.com
Additionally, is this Windows 7 32 or 64-bit and what specific errors are you getting? Also, are you downloading the drivers directly from the Realtek website or from your computer manufacturer's website?