GPU-Z v0.4.7 now has proper support for the NVIDIA GeForce GT 430/420 video card series.
Grab it if you want to use the latest and greatest - http://www.techpowerup.com/downloads/1882/mirrors.php
GPU-Z is a lightweight utility designed to give you all information about your video card and GPU.
Changes in GPU-Z 0.4.7
Improved support for AMD Radeon HD 6850 and HD 6870
Added support for NVIDIA GeForce GT 430, GT 420
Fixed default clock reading on Fermi architecture cards
Added voltage controller support for Colorful iGame GTX 460
Added PCI Vendor detection for Colorful
Added TMU count and die size for GF106
Synchronization mutexes are global now
Improved stability when running multiple instances of GPU-Z / Fixed "the driver has been marked for deletion" error