It's portable bootable linux on the Go. But might not work on older system.
NOTE: Make sure stable cable connection at all times, else entire OS will hang. Just don't touch the cable...
----- Update 20110907 ----
TIPS: Look for PCs or Notebooks that feature "firm-bite" USB connector. Well, what I mean is it sort of "clipped", feels stable and don't come loose easily. Eg: Acer Aspire 5830TG - TimelineX.
Booted OK on
i) ASUS P8Z68-V Pro, intel i7 2600k, 8GB RAM (Home Set)
ii) Acer Aspire 4736Z (Work Set)
iii) Acer Aspire 5830TG - TimelineX (Temp Test Set)