Short bio: Computer Scientist, FOSS supporter (read more)
Tux Machines (TM)-specific
I compared the hardware requirements of a popular Linux Desktop: Ubuntu 9.10 with Windows 7 both of which were released last month.
Hardware Windows 7 Ubuntu 9.10
RAM (MB) 1024 MB 256 MB
Processor (MHz) 1000 MHz 300 MHz
Disk Space (MB) 16 GB 4 GB
Ubuntu 9.10 remained a modest 265MB memory with 300MHz computer. Also Ubuntu can run on lesser hardware as well, if you have 128MB Memory, you can still use Xbuntu (a variant), or if you have 64 MB you can use LTSP and run Ubuntu off a central server.
Now Windows 7 demands 1GB Memory with 1GHz computer.
While Windows 7 required 16GB of space to install, Ubuntu can be installed on on less than 4 GB of space.