Are you saying you downloaded and installed the MS Vrtual PC and now what to restore a backup of XP onto a VM?
That won't be possible! If you had previous created a Virtual Hard Disk(VHD) where XP was custom installed to you might have better success.
For the MS VPC the XP Mode option is the first option there for running the virtual version of XP Pro. With SP1 installed you no longer need to download the VPC separately from the XP Mode as two items needing separate installations but a newer combined XP Mode installer.
For seeing XP Home instead running on a VM you first need to download and install a VM player or create a VHD. The Oracle VirtualBox or VM Player 4.02 presently the latest release are two 3rd party option for creating a new VM for XP. VBox in particular can also be used for Vista, 7, and now the next version's Release Preview as well as other OSs on a virual platform.
The Acronis backup you made in the meantime would have to be restored to a physical XP install to hard drive in order to see that data once again available. A full system image backup would be restored to a physical hard drive.