Debian does not impose hardware requirements beyond the requirements of the Linux kernel and the GNU tools.
Rather than attempting to describe all the different hardware configurations that are supported for the PC platform, this section contains general information and pointers to where additional information can be found.
There are two excellent places to check for detailed information: the Debian System Requirements list and the Linux Documentation Project Hardware Compatibility HOWTO. For information on video card support, you may also want to look at the XFree86 Project web site.
You must have at least 4MB of memory and 35MB of available hard disk space. If you want to install a reasonable amount of software, including the X Window system, and some development programs and libraries, you'll need at least 300MB. For an essentially full installation, you'll need around 800MB. To install everything available in Debian, you'll probably need around 2GB. Actually, installing everything doesn't make sense because some packages provide the same services.