Hi, I have a portable SSD with Linux Mint MATE, 32 bits version. For old PCs with small memory (or just for fun) I use the i3-wm. I also have Linux Mint on an old EeePC 901, which is very slow. For the EeePC I use i3 as default wm.
The config is configured in a way which sets buttons, colors, letter rendering etc. to what I have configured for MATE. This is done by calling the mate-settings-daemon on start up of i3. You'll see that in config. (However, the cursor settings from the MATE configuration only work in some apps. This is a minor issue.) The config is here: http://wahlspezial.de/modified-i3-configuration-from-wattos-r9-microwatt-for-linuxmint-17-1/ (The config is based on the i3 config of WattOS R9 MicroWATT, which is a nice distro too.) Have fun, Goetz