Each method of installation has pros and cons. In the case of a Portege 3500, only some external USB CD drives are bootable through the system BIOS. These drives are sometimes available on eBay or through laptop parts dealers. However, they often cost $200 or more, and they may only boot certain CDs (such as System Restore CDs) and not others (such as a standard OS installation CD).
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Step 3

For newer laptop and netbook models, USB thumbdrive installs are another cheap OS installation option. However, the Portege 3500's BIOS does not support boot-from-USB for thumbdrives. So, instead, this article will explain how to prepare the laptop's hard drive for OS installation by way of a USB external enclosure.

(Note: If you will need to reinstall the same OS on several computers in a short amount of time, consider looking into network install options. The Toshiba Portege 3500, and many other legacy laptops, support this option.)
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Step 4

To begin, turn the laptop off and remove the battery and AC adapter. Use a Phillips screwdriver to access the laptop's hard drive bay. A small plastic tab is attached to the hard drive in the Portege 3500. You can gently pull on this tab to remove the hard drive. (For more detailed instructions on accessing the hard drive in this and other laptop models, refer to the excellent disassembly guide provided in the "Resources" section below.)
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Step 5
Example of a 2.5

Example of a 2.5" IDE to USB External Enclosure

The standard hard drive in a Portege 3500 uses an IDE interface. Using a USB external enclosure designed for 2.5" IDE drives, attach your laptop's removed hard drive to another computer with a USB cable. (A variety of external enclosures are available for purchase online. You can purchase one for about $10 from one of the links in the "Resources" section below.)
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Step 6

Use any format utility to partition and format the USB drive as desired. You must make at least one primary partition of size 1.5GB or greater, formatted in FAT32. Mark this partition as active. (If you are using Windows XP to do this step, further details are available in the eHow article entitled "How to Mark a Partition as Bootable in Windows," linked in "Resources" below.)
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Step 7

Once the USB drive has been partitioned and formatted, insert your Windows XP disk into the extra computer. Using a file manager, copy and paste the contents of the Windows XP CD to the active FAT32 partition on your USB drive.
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Step 8

Disconnect the USB drive from the extra computer and remove the 2.5" IDE to USB adapter. Reinsert the drive into your laptop. Reinsert the laptop's battery and plug the laptop in with its AC adapter.
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Step 9

Boot up the laptop. With any luck, you should be presented with a DOS prompt. If you do NOT get a DOS prompt at this point, check that your drive is formatted with the FAT32 file system and is marked as active. If you still cannot get a DOS prompt, you may need to use a USB floppy drive and bootdisk to begin the OS installation. (For details on how to create and use a boot floppy, refer to the eHow article, "How to Use a Bootdisk to Begin an OS Installation in DOS," linked in "Resources" below.)
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Step 10

Navigate to the drive letter where you copied the Windows XP CD installation files. (This is usually C:\) Access the folder "i386" on this drive, and run the file "winnt.exe". This will begin the OS installation process. It will take about 2~3 hours for the initial setup files to be copied to the hard drive. Once they are, you can restart the computer, and the Windows installation process will automatically begin.

Read more: How to Reinstall Windows XP on a Toshiba Portege 3500 | eHow.com http://www.ehow.com/how_5056670_reinstall-windows-xp-toshiba-portege.html#ixzz0wUPoTZHJ