There are a lot of different builds of Puppy, giving you many choices and possibilities:
Puppy 5.3.3 'Slacko' is our latest 'Woof2' built official Puppy, it is highly Slackware compatible. Recommended for most new users. Also available is a 5.3.3 Puppy Slacko version with ALL the software included FatSlacko. Also available is a cut down 99MB version
For efficiency on older hardware try Wary 5.3. Puppy Wary is compiled in Puppy using a mature kernel. Racy 5.3 combines Wary and the up to date 3.04 Linux kernel.
There is a big list of different Puppy versions, also see versions under development.

Clean installs are recommended for new Puppy versions, see Installation Index

Barry Kauler (Puppy's creator) currently actively supports and maintains Wary (old hardware) and Racy (newer hardware), see his blog for the latest updates.

Slacko is not compatible with Woof1 built Puppy 5.2x Lucid - which was our recommended Puppy for the last two years. Many utilities from Lucid are available for Slacko in the LupufySlacko package.

What puppy Linux is best for you
Installation Index
Puppy Version Under Development

Puppy official page
Barry Kauler's blog
64bit and multicore Puppy list
One stop Puppy Version 'shop'
Puppy Linux Repo - distro list and host
Puppy Linux Links - Puplets