Epson Stylus NX420 All-in-One Printer Drivers and software download page for Windows and Macintosh.
OS: 
Windows 7 (32-bit, 64-bit), Vista (32-bit, 64-bit), XP (32-bit, 64-bit), 2000.
NX420 Scanner Driver and EPSON Scan Utility v3.770 Download (12.39MB)
File Name: epson17431.exe
NX420 Drivers and Utilities Combo Package Download (82.31MB)
File Name: epson13800.exe
This file contains everything you need to use your Epson Stylus NX420 wirelessly or wired.This combo package consists of the following items:
- Printer Driver v6.71
- Scanner Driver v3.770
- Status Monitor 3
- Event Manager v2.40.01
- Network Installer
OS: 
intel-based Macs with OS X (v10.4.4 – v10.5.x), PowerPC Macs with OS X (v10.4.x – v10.5.x)
Scanner Driver and EPSON Scan Utility v3.77 Download (16.64MB)
FileName: epson15958.dmg
NX420 Printer Driver v8.26A Downlaod (24.25MB)
FileName: epson13891.dmg