The external HDD would have to be connected to the computer using an e-SATA connection without any adapter so that Windows 7 will think that the externall HDD is the same as an internal HDD. It will not work with any other type of connection.
If you do have that type of connection, then you can just follow METHOD TWO in the tutorial to install and dual boot with XP.
A very grateful user says a big thank you for these oh so easy guides - have successfully loaded Win 7 onto a second disc and changed the name of the existing op system by using EasyBCD and amazingly for a complete non techie it all works
System Manufacturer/Model Number Custom Built OS Windows 7 Pro 64-Bit CPU INTEL Pentium D950 (2x3.4GHZ) 800mhz FSB/2 x 2MB Cache Motherboard ASUS P5WD2 Premuim: Dual Core DDR2, 16VGA - 3 PCI/2 PCI-EX Memory 4GB DDR2-533 PC4200 Graphics Card ATI Radeon HD3800 Series Sound Card Realtek ALC882D 8 Channel Monitor(s) Displays No1 = ACER P223w / No2 = ACER A1751
Keyboard Logitec LX710 Mouse Logitec Laser PSU Silent 500 Watts + 120mm Fan Cooling 2x120mm case fans, 100mm CPU fan Hard Drives Main 250GB Weston Digital 5400rpm (XP sp3)
Back-Up 750GB Weston Digital 'Caviar Green' 7400rpm
Windows7 64Bit on a separate 750mb Weston Digital Internet Speed 4.8Mbps
My first attemt at this.
I found a different web page to start the process.
I didn't know this was even here.
Everything was fine until I reached your Method 2- Step 7.
The other site forgot to include this so Easy BCD won't open.
After a few choice words and the mandatory Google search I thankfully found your article.
Read it from end to end found the errors of my way Method2- Step 7 and it WORKED!!!!!!!!!!!
System Manufacturer/Model Number Hopalong/ Godzilla OS Windows7 Pro 64bit SP-1; Windows XP Pro 32bit CPU Intel Core i7-870 Lynnfield 2.93GHz LGA 1156 95W Quad-Core Motherboard ASUS P7P55D-E PRO Memory 8GB@1400MHz Crucial Ballistix DDR3-1600 4x2GB Graphics Card ASUS ENGTX460 DirectCU/2DI/1GD5 1GB 256-bit GDDR5 Sound Card VIA Onboard Monitor(s) Displays Asus VS248H-P 24"; Samsung SyncMaster 941BW 19"ws Screen Resolution 1920x1080; 1440x900
Keyboard Logitech K-320 Mouse Kensington PSU COOLER MASTER Silent Pro RS850-AMBAJ3-US 850W Modular Case COOLER MASTER HAF 932 RC-932-KKN5-GP Black Cooling Scythe "Mugen-2 Rev.B" (2 ScytheKaze-Jyuni PWM fans) Hard Drives Samsung 830 120GB SSD
Intel 320 120GB SSD
Western Digital Caviar Black WD7501AALS 750GB 7200 RPM SATA 3.0Gb/s
Western Digital Caviar Black WD6401AALS 640GB 7200 RPM SATA 3.0Gb/s Antivirus Avast Inernet Suite Browser IE 9 ; Chrome
System Manufacturer/Model Number Gateway GT5692 OS Windows 7 Ulti. x64 CPU AMD Phenom 8450 triple-core 2.10 ghz Memory 4GB Graphics Card ATI Radion HD 3200 Monitor(s) Displays Gateway FPD1775W Screen Resolution 1280x720
System Manufacturer/Model Number Hopalong/ Godzilla OS Windows7 Pro 64bit SP-1; Windows XP Pro 32bit CPU Intel Core i7-870 Lynnfield 2.93GHz LGA 1156 95W Quad-Core Motherboard ASUS P7P55D-E PRO Memory 8GB@1400MHz Crucial Ballistix DDR3-1600 4x2GB Graphics Card ASUS ENGTX460 DirectCU/2DI/1GD5 1GB 256-bit GDDR5 Sound Card VIA Onboard Monitor(s) Displays Asus VS248H-P 24"; Samsung SyncMaster 941BW 19"ws Screen Resolution 1920x1080; 1440x900
Keyboard Logitech K-320 Mouse Kensington PSU COOLER MASTER Silent Pro RS850-AMBAJ3-US 850W Modular Case COOLER MASTER HAF 932 RC-932-KKN5-GP Black Cooling Scythe "Mugen-2 Rev.B" (2 ScytheKaze-Jyuni PWM fans) Hard Drives Samsung 830 120GB SSD
Intel 320 120GB SSD
Western Digital Caviar Black WD7501AALS 750GB 7200 RPM SATA 3.0Gb/s
Western Digital Caviar Black WD6401AALS 640GB 7200 RPM SATA 3.0Gb/s Antivirus Avast Inernet Suite Browser IE 9 ; Chrome