[JohnE]

I've recently renewed my PC due to failing CPU creating an uneconomical repair. The new PC comes with Windows 7 Home Premium installed. Have found that more than a few programs and associated files & Folders on my old unit {XP (3)} and 7 yrs old are both incompatible and unreadable on 7. If possible, the cheapest way to overcome the problem is to install the HDD from the old unit and run the two of them, isolated and independant of each other.
Has anyone done this? Does it work w/out prejudicing either of the 2 OS's or their associated files & folders.
If it can be done.....what is needed to achieve it?

[Grav!ty]

It cannot be done, for the simple reason that your hardware is totally different and the drivers for the various hardware items will differ.

You can if you have your XP CD, run a repair install once you have the old hard drive installed in the new system and that will leave your software intact, although you will need to install fresh XP drivers for your new hardware IF they are available. You will also need to re-validate your XP license, which strictly speaking is not transferable from computer to computer.

Once you have XP successfully running on the new computer, you will need to set up a dual boot - see these guides:

install-windows-xp-in-dual-boot-with-pre-installed-windows-7-t112568.html

dual-boot-trouble-shooting-guide-xp-windows-7-running-t112569.html