For this part I used IsoBuster and Nero Burning ROM 6 (make sure you have the latest version, but at least 184.108.40.206).
(do a google on it)
After you install IsoBuster, you can choose to use only the product's free functionality for what you want to do (you need to have your original Windows XP CD in the CD-ROM drive).
Start to extract the boot loader from the original Windows XP CD. Using IsoBuster, select the "folder/Icon" Bootable CD, and right-click Microsoft Corporation.img. From the menu choose Extract Microsoft Corporation.img, and extract it to the folder on your hard drive where you have your Windows XP files.
Next, start Nero Burning ROM, and choose CD-ROM (Boot) in the New Compilation window. On the Boot tab, select Image file under Source of boot image data, and browse to the location of the Microsoft Corporation.img file. Also enable Expert Settings, choosing No Emulation, and changing the Number of loaded sectors to 4 (otherwise it won't boot!)
Under the iso tab select max 31 chars and Mode 1 leave everything checked.
Under label tab just label the cd same as your original.
Next press New, and from the File Browser window, select the files and folders from your slipstreamed location . Now drag & drop the selected files in the ISO1 window.
Hit Burn :bigsmile: