Ever tried it? It is not for the faint of heart as just getting it to install required that I delve heavily into the terminal, but if you are looking to get a OLD computer up and running for light tasks just as fast as your new Core i7 give it a try.

http://www.damnsmalllinux.org/

To give you an idea, I installed it under a virtual machine, and only gave it 64 mb of ram, and it running basic tasks faster than the host, and only using 22 mb of ram in the process.

Like I said, several things are done very differently from other linux distros that you may have been used to but here's the quick and dirty.

Boot up off the iso
Open terminal
run "sudo su"
run "cfdisk"
Use cfdisk to partition your drive as primary, bootable, and having a linux FS (there is a gui)
Open DSL>Apps>Tools>Install to hard drive and follow the prompts
Reboot, and you should be good to go, the whole install process only took me about 45 seconds start to finish, it really is damn small.

DSL is based on debian, so when you restart you can run "sudo dpkg-restore" to get some apt-get functionality, but so far, my experience has been mixed. On the plus side, firefox is installed by default.