Puppy 4.00 was a major upgrade from 3.01, with just about everything overhauled and updated. Version 4.1 continues the hectic pace of development, with ground-breaking new applications and under-the-hood architectural improvements over 4.00. Ground-breaking apps include our new Psip VOIP and PPLOG personal blog. Under-the-hood includes faster boot times, much better hardware detection, and new 'pup_event' architecture (including desktop drive icons). The live-CD file is 'puppy-4.1-k2.6.25.16-seamonkey.iso' at 94.1MB and 'puppy-4.1retro-k2.6.21.7-seamonkey.iso' at 94.6MB. The latter is a more conservative kernel that perhaps suits older systems.