Download Driver Laptop and Printer

1.First make Vista backup. How to do it all informations here.

2.Update Your Bios here.
This is very important for this model. If You will not do this Your audio may not work in XP.

Now You need to slipstream Your Sata drivers (only ICH9M) with nLite.
Download Nlite: Download
Download sata Drivers: Download

Read the Guide here: Slipstream Guide

Be sure also that You are using WinXP SP2 version. If you haven't got SP2 version here you can download this service pack: Download

You need to create a new XP cd to install window XP on this laptop. So to do that we need to perform a process called slipstream.

Materials need to download:

Nlite: Download
Intel ICH9M-E/M SATA AHCI Controller Driver: Download
Windows XP sp2 patch: Download

and then follow this instruction: here

Update Your Bios here. There are big changes in this new version.

Here is the guide to install XP,

First make vista backup:here

Prepare this material:

Download Nlite: Download

Sata controller: Download
32-bit Floppy Configuration Utility

A blank CD

You have to create a new windows XP CD using the one that you have:
Here is the guide to slipstream: GUIDE

Compaq Presario CQ40-401AU is design for windows vista. Installing windows XP driectly using original windows XP CD will result in Blue Screen Error or " No hdd was found".

There is a famous trick to solve this problems which know as slipstream guiide to install windows XP. Slipstream process is not too difficult but for this model which use AMD sata drivers it can be a little bit tricky.

You can read how to slipstream guide here, something worth to mention is:
1. Make sure to use right sata drivers.
2. If you are about to repeat the process, delete all folders and create new folder.
3. If you failed 2 - 3 times, that normal.
4. Windows XP SP2 is preferable.

TUTORIAL LINK: Slipstream Guide to Install windows XP

Your driver maight not work completely if you fail to install it according to order, this method order is the best i ca find, the most important things is when installing driver the chipset come first and the either AUdio or graphic.

Based completely on HP available softpaqs:

1. NX9420 BIOS vF.1a (plus CMOS "Set Defaults")
2. Seagate HD Firmware v1.00a (if applicable)

(Install Windows XP)

3. Intel Chipset Support 7.2.2.1006a
4. ATI or Nvidia, depending on what you have
5. ADi SoundMAX v5.10.01.4321
6. Microsoft UAA Bus Driver v1.00 A6
(might need to swap order of #5 and #6)
7. Broadcom GbE NIC v8.48.0.0
8. Conexant or Agere Modem Driver, depending on what you have
9. HDA Modem Installer v1.00 B
(might need to swap order of #8 and #9)
10. Intel or Broadcom Wireless NIC, depending on what you have
11 HP Integrated Bluetooth v4.00G
12. HP Wireless Assistant v2.00E
13. TI Media Card Driver v2.0.0.6a
14. High-speed SD Card Driver v1.0.0.0a (read Release Notes first!)
15. HP Mobile Data Protection System
16. Authentec Fingerprint Driver v1.00D (if applicable)
17. HP ProtecTools Security Manager v2.00D
18. HP Credentials & FP Manager for PT v2.00D
19. HP Embedded Security & TPM Driver v4.50a
20. HP Bios Configuration for PT v2.00c
21. HP Device Access Manager for PT v2.00a
22. HP SmartCard Module for PT v5.00d (if SCM is installed)
23. JavaCard Security for PT v1.00B (if using JavaCard)

The following are the "optional" items (no particular order):

* HP Battery Check v1.00a
* Synaptics Touchpad Driver v9.1.11Q
* Help and Support Center v4.4C
* HP Accessories Product Tour v13.00
* WinDVD Player
* LightScribe Host Software 1.4.105.1 N (if using a LightScribe drive)

I'm not aware of any "requirement" to install QuickLaunch 6.00 before 6.30 nor is there any mention of it as a prerequisite in the release notes.

Taking this a step further, I would install the "latest" versions of the following instead of the ones available on HP's website:

3. Intel Chipset Support v8.1.1.1010 from Intel's website
4. Latest WHQL driver from either ATI or Nvidia website
7. Latest Broadcom B57xx driver from Broadcom's website
(plus BACS utility found under "NetXtreme II"
10. Latest Intel Pro/Wireless NIC driver and client from Intel Website.

After all this, Windows Updates.

Again, I've never worked on an NX9420, but this is how I'd approach it.

- nn6o

For reference:

http://downloadcenter.intel.com/
http://www.broadcom.com/support/ethernet_nic/downloaddrivers.php
http://ati.amd.com/support/driver.html
http://www.nvidia.com/content/drivers/drivers.asp