Very short answer: none.
I am assuming that you mean that your system is running Win7 and you want to attach the Maxtor 80 GB One Touch. There's a 200 GB One Touch under my desk here at work, and I don't need drivers. It's generic USB plug-and-play.
On the other hand, if you want to use the One Touch feature, you have to install software that should have come on a CD with the device. Well, in some cases it was on the device itself - bad idea, in case you have to reformat, but look on the drive and see if the software is there. Here is where you can download the SW:
http://www.seagate.com/ww/v/index.jsp?locale=en-US&name=ot4-downloads&vgnextoid=0ed72c9e46914110VgnVCM100000f5ee0a0aRCRD . Are you running 32-bit or 64-bit; when I scanned the downloads it looked like 32-bit only.
Look on the drive itself first for something named
launch.exe in the root folder; if it's there, that's the simplest approach.
If, on the other hand, your issue is that you plug in the drive and can't see it in Windows, that's another issue