Locked out of Windows XP Professional

It is  a pretty decent laptop - perfect for the daughters needs.  How do I even get into the computer to "wipe it clean"?  By that do you mean reformat the hard drive and reload programs?

Insert Dell XP Professional / Home disc and switch off your C840 press and hold F12

Follow the instructions for installing XP Professsional / Home, opt to do a full format of the C: drive and select that partition to install.

Meanwhile... Download the following onto another machine and copy to a CD/DVD flash drive or external hard drive:

Copy the following to a CD or DVD or external hard drive.

1. Download XP Service Pack 3:

http://www.microsoft.com/downloads/details.aspx?FamilyID=5b33b5a8-5e76-401f-be08-1e1555d4f3d4&DisplayLang=en

Download the following drivers from here:

http://support.euro.dell.com/support/downloads/driverslist.aspx?c=uk&cs=ukdhs1&l=en&s=dhs&ServiceTag=&SystemID=LAT_PNT_P4_C840&os=WW1&osl=en&catid=&impid= 

2. Dell System Notebook Software Under System Utilities (Other stuff in system Utilities should be covered with Service Pack 3, note need to have Service Pack 1 or 2 on your disc (Says on disc) before installing Service Pack 3)

3. The Chipset drivers Under Chipset

4. Then the Nvidia Video Driver (Not the BIOs) Under Video

5. Then the  Conexant Driver Under Communications and other appropriate ones

6. Then the appropriate Drivers Under Network

7. Then the Sigmatel Driver under Audio

8. Then Glidepoint / Stick Pointer under Input Devices

9. Then the Dell Access Direct under Applications

10. Install the two Dell Diagnostic Drivers

11. Go here: http://www.istartedsomething.com/20061029/royale-noir/ and you can download a Black XP and XP Media Centre Edition Colours.

12. If using msn messenger download from here: http://www.softpedia.com/get/Internet/Chat/Instant-Messaging/MSN-Messenger-8.shtml and download this http://www.apatch.org/ to customise the messenger and get rid of adverts.

13. Download and install windows media player 11 and the Klite Codec Pack:

http://www.microsoft.com/downloads/details.aspx?FamilyID=1d224714-e238-4e45-8668-5166114010ca&DisplayLang=en

http://www.softpedia.com/progDownload/KLite-Codec-Pack-Download-16475.html

14. Also recommend you download and install Adobe Reader 9 and PDF Creator here in order to read and print PDFs:

http://www.adobe.com/

http://sourceforge.net/project/showfiles.php?group_id=57796

Ok now install all the drivers in the order I specified. (11. - 14. Optional) 

Then go to xp and install all other such as antivirus and office programs copy music and documents over etc. Be sure to go to windows update to get internet explorer 7 aswell.

I found a Windows XP Home Edition CD which belongs to my other desktop computer.  Can I just use this on the laptop with the XP Professional on it? Believe it should have the home edition anyway, since it's not used in an office anymore.  Will all my drivers be erased? If so, will I just need to download those from dell.com?  Will I lose my ability to connect with the wireless internet in the house after reinstalling Windows?  Thanks for your help so far....

You will be breaking your license agreement by doing that. If it is a Dell xp home disc it may work and yes everything will be lost you will need to download drivers from the Dell website.

Also you may want to either slipstream or download and then install XP Service Pack 3 before going online, again need your computers model to direct you to proper drivers and install order.

Thanks so much for the info - will work on this today and let you know how it goes -