You can’t just put the drive from one computer into another and have it boot from that because of the differences in motherboards, chip sets, drivers, etc. unless the systems are totally identical. You could put it in and access the data on it as a secondary drive, though.
I downloaded an application I wasn't too crazy about and when I moved the icon to the trash can, it disappeared without a trace leaving zero remnants behind.
I know I sound like an Apple fanboy but there you go. This is my experience with my first Apple system.
Why not use Mozilla Thunderbird as your default mail client? Or just eschew a local mail client altogether and use the online interfaces? Going back to WinXP will open you up to a host of compatibility and security issues. Win7 is a good OS.
I've done it in the past. It's painful, not pretty, and overall it's a lot easier to just bite the bullet and deal with the new system as such. At least in my experience.
Install Windows Virtual PC and Run XP Mode. Outlook express is there, however I have no problems with Windows Live. I do use XP Mode for a couple of apps that won’t run in Windows 7.
Understand that if your machine is a 64bit box, and your old XP system is 32bit (which is likely), you will certainly lose performance, and that in a very noticeable way, as XP will not be able to use the full capability of the CPU, and will only be able to use 3 gigs of RAM - This is not necessarily a game-changer, but it is certainly not the best scenario - You will want to be able to use the machine to it's full capacity.
If you still want to move forward, it would certainly be best to pay a service tech to do the retrofit, and it will probably save you a lot of headaches. This is not an easy thing to do.
Before even beginning, do the research to figure out whether XP drivers are available for that specific machine... You can do that by looking the machine up on dell to see if Dell provides legacy drivers for it. I will bet you dollars to donuts that XP drivers are not available, as that is most often the case. If the drivers are not available, you are just boned.
Then one must be sure that the old drive will fit the new slot - one may be a PATA (old) style drive, while the new box will certainly be a SATA (new style drive) - If your old drive doesn't fit, the work is doubled... still technically possible, but one would have to obtain a drive that would work, and image your old drive onto it - A pretty technical adventure for one who is uninitiated.
Lastly, while one can hack the registry from Safe Mode to remove the vestiges of your old machine drivers, allowing the box to detect new hardware on boot, it is never the best way to do it - A clean install is proper, and most likely to be a successful process. So IF you do decide to retrograde the system, starting from scratch install would be my recommendation. You will need the XP key from your old machine, and an XP setup disk (probably OEM, must know if XP64 or XP32)... and if your old hard drive will not bolt, another hard drive to use.
DO NOT use the current (new) hard drive in any circumstance (unless of course, you are continuing to use it as a WIN7 box), as it contains the information to put the machine back to it's original factory package - something you will probably want, at least to restore it to pristine for resale purposes.
And finally, I would encourage you to move forward with Win7 as XP is now a legacy system - Even if you can shoehorn it into the present box, the next box you get will almost certainly not be able to use XP, and you may well be on an even steeper learning curve with Windows 8 (or 9, 10, etc) than you already have with Win7. Time waits for no man.
Try moving your mail to Mozilla Thunderbird, which will be more likely to remain relatively unchanged between windows iterations, and even between operating system platforms (works in Linux too). In any case, it is not a good idea to stay in Outlook Express (which you probably used in XP), as it has known exploits, and is not able to defend against some viruses.
If you used Outlook rather than Outlook Express, then all this is for naught, as all you need to do is install Office and move your .pst file from the old to the new, and you will be right where you were, but on the new machine and in Win7 :)
My work just gave me a new computer w/ Win 7 Pro.
Hate it. Esp Office Outlook.
Yesterday I logged off the network back to my C drive. Black screen w/ icons.
My pretty desktop gone. Down in the tray was a notification..
‘The Windows you are running is not genuine’. Huh ??
Rebooted. A panel appears ‘ The Copy of Windows is counterfeit.”
That is baloney ! Took the IT guy about an hour to get it going.
Long for XP.
But then I come home, fire up the Mac and all is well.
If the XP on the drive you want to use was installed on a different PC then your devices will not work properly. Even if it did, you would have an issue with XP wanting to re-activate because all you hardware has changed.
You would be better off running XP in a virtual machine from within Win7. I believe Win7 has Microsoft Virtual PC already on it. Just make a VM and install your WinXP on it. You may have to re-activate. That's a much slicker solution.