Let me introduce antix ,
Tested on old both laptop & netbook and found really satisfactory. Strongly recommend this OS to all friends who would like to gain fast/reliable and secure performance on their computers.
So What is antiX? See below quote from offical page,
antiX is a fast, lightweight and easy to install linux live CD distribution based on Debian Testing for Intel-AMD x86 compatible systems. antiX offers users the "antiX Magic" in an environment suitable for old computers. So don't throw away that old computer yet! The goal of antiX is to provide a light, but fully functional and flexible free operating system for both newcomers and experienced users of Linux. It should run on most computers, ranging from 64MB old PII 266 systems with pre-configured 128MB swap to the latest powerful boxes. 128MB RAM is recommended minimum for antiX. The installer needs minimum 2.2GB hard disk size. antiX can also be used as a fast-booting rescue cd.
At the moment antiX-13 "Luddite" comes as a full distro (c690MB), a base distro (c400MB) and a core distro (c135MB) for 32 bit and 64 bit computers. For those who wish to have total control over the install, use antiX-core and build up.
Present released version, 20 June 2013: All isos and md5sum files available 'Luddite'
Source : http://antix.mepis.org/index.php?title=Main_Page