you might also check to see if the drivers are available via windows update.  as long as you've installed the chipset driver, windows update often will be able to detect and provide drivers.  if drivers are available, they will appear in the Advanced windows update, under Hardware.

Excellent ! Thanks to eXpeLLed_4RM_heLL ! Unfortunately, the second link (Beanbag Emulation Device) doesn't work... Could you give it under a different form please ? (no need to translate anything, I do speak French, German, English and Russian). Thanks in advance !

Just to summarized :
To downgrade an HP Pavilion Elite m9140.ch from Vista to XP, you need :
1. first shoot out Vista, you really don't need it
2. install XP with a genuine version
3. drivers can be found here :
3.1. motherboard Asus M2N68-LA (HP "Narra3-GL8E") has no XP drivers but it really doesn't matter
3.2. processor xp driver Amd Phenom can easily be found on the amd web site
3.3. graphic card nvidia geforce 8600GT driver can easily be found on the nvidia web site
3.4. chipset nforce 430 6150SE can also easily be found on the nvidia web site
3.5. audio and sound card drivers are based on a Realtek ALC 888S chipset and can be found here
     (for example) http://www.drivers-software-download.org/tag/realtek-alc-888s-chipset
3.6. 802.11 WLAN driver can be found here :
     http://www.ralinktech.com.tw/data/drivers/IS_AP_STA_7x_D-1.3.0.0_VA-3.1.4.0_2500_D-2.1.1.0_VA-3.1.0.0_RU-2.1.1.0_VA-2.1.1.0_AU-2.0.0.0_VA-2.0.0.0_030508_0.1.0.46.exe
3.7. TV Tuner driver :
     http://www.wintvcd.co.uk/drivers/HVR-12x0-14x0-17x0_1_25_25271_WHQL.zip
3.8. "Beanbag Emulation Device" is a bit more tricky :
     (found on HP forum: http://forums12.itrc.hp.com/service/forums/bizsupport/questionanswer.do?admit=109447627+1224007014255+28353475&threadId=1274208)
     "1. You need to copy irbus.in_ and irbus.sy_ from an XP CD (Pro SP2 seems to work, don't know about others) to the local computer. Search for these files from the XP CD.
      2. use command line (Start --> Run --> cmd.exe) to expand the files.
         expand irbus.in_ irbus.inf
         expand irbus.sy_ irbus.sys
      3. In Device Manager, look at Beanbag Emulation Device's Properites --> Details --> Device Instance Id. Copy the displayed string.
      4. edit the irbus.inf file, go to the [MicrosoftHw] section to add the line %USB\VID_045E&PID_006D.DeviceDesc%=IrBus, USB\VID_147A&PID_E018&MI_00
         Notice the strings after the comma should match what you had copied in step 3 above. Mine had some extra backslash and characters after MI_00, but they didn't seem necessary.
      5. Save the edited irbus.inf file.
      6. Back in Beanbag Emulation Device's Properties, under Driver tab, select Update Driver.
      7. Don't connect to Windows Update
      8. Install from a list or specific location
      9. Search for the best driver, include this location in the search (Browse to where you saved irbus.inf and irbus.sys)
      10. Confirm a few prompts and you are good to go!
      11. After installation, the device is called eHome Infrared Receiver Properties."

That's it, and it works ! No more "?" in the Device Manager...
THANKS TO EVERYBODY WHO FIGHT AGAINST A CERTAIN MICROSOFT POLICY...
pw

i object.
it seems to me that eXpeLLeD_4RM_heLL gave some level of assistance and deserves more than 0 points.

the question asked for help finding drivers, not a step by step walkthrough for how to downgrade a laptop from vista to xp...

moreover, padraig62 actually uses the information provided by eXpeLLeD_4RM_heLL as part of the "final solution" in #22713964