If I install Windows 7 on my old XP as a clean installation, is there a way
to transfer my data without messing up the new installation?
Yes, there is. In fact, it’s the only officially supported way to install
Windows 7 on a machine that’s running Windows XP.
It simply requires some preparation.
A “clean” install of Windows treats the system hard disk as if it were empty, which of course it can be.
If it’s not empty, then a clean install either:
makes it empty by reformatting the disk as part of the installation process (which I actually recommend, since the next point is so confusing)
ignores everything on the disk and loses track of all installed programs and data files. The files may all still be there, somewhere, but the applications you might have used to access them are not installed as far as the new OS is concerned.
The bottom line is that your data’s either gone, or difficult to find.
And in either case, a clean install requires that you now reinstall all the applications you had been using on your machine, from scratch.
By far the best approach is to prepare for your clean install with a full backup of everything. That way, no matter what you may lose as part of the installation process, you’ll always have it available from that backup.
As I described in How do I upgrade from XP or Vista to Windows 7?, the steps work out like this:
Backup so as not to lose any of your data, and as a place to revert to should your installation below fail. Make sure this works.
Install Windows – a clean install, ideally reformatting the hard disk so as not to leave clutter around after the install
Install Applications – from their original installation media or downloads
Restore your Data – from your backup
The net result of this process is a clean machine, running the new operating system, with all your applications and data transferred safely.
It’s a bit of work, and as I said, perhaps the most important step is the preparation.