My Dell Latitude D600, an 8+ year old laptop, Pentium M 1400Mhz, 1.25gb RAM.
http://www.dell.com/downloads/us/products/latit/d600_spec.pdf
On identical speed (5400rpm) Hitachi hard drives:
One with Windows XP Pro
One with Peppermint OS (linux based OS)
http://www.peppermintos.com/
On start up they both immediately run Chrome Browser.
Conclusion: if you have an old computer laying around and you hate how slow it is, use Peppermint to breath some life into it!