Sites like 4PDA and GPS Power (registration required) host various "builds" optimized for different screen resolutions like 800x480. Step-by-Step Installation Guide

The safest way is to purchase a pre-loaded MicroSD card from specialized retailers like NaviShop or Amazon . These often include 30 days to 3 years of free map updates. Community & Manufacturer Links:

It runs smoothly on devices with as little as 64MB to 128MB of RAM and a 400MHz+ CPU .