install on disk with data

Is it possible to install xp on disk where are some data, files, so that these files will be kept? Its just data disk, not system at all, never was. Thank you.

Put the files in a separate partition. You will need to use 3rd party partitioning software that is capable of changing partition boundaries whilst preserving contents. (I usually use Partedmagic

Then do your Windows install into remaining free space that you have created in what is left over after you have performed above action.
ps Put the data partition at the end of the disk. Less problems then wrt getting Boot sector satisfactory when you install OS.
Or, back up your files to a flash drive and then wipe entire drive with a slow format and then you can create your partitions on the drive at install time. and replace your files on your new partition, :)