Problems in Windows XP

Under WIN 7 everything went smoothly, at start-up of the laptop is felt slower. After a full scan, it displays no harmful files, which frankly surprised me somewhat because Malwarebytes has found a file a few days ago that I had not cleared ....
Because this software includes 2 licenses, I want to install it on my PC with Windows XP SP3 (lt. Packaging is this version support) but I can not activate the Internet to the program after installation. At the DSL connection, it is not because the laptop easily goes into the net with Win 7. The Help Forums Kaspersky are formulated pompously that one is overburdened as a layman. Hotline number. None - means there is only one account that needs to be created, and for me a little too much freedom with the files that are to be transmitted to troubleshoot permits.
I had before installing KIS no virus software more on the laptop / PC and free space is also sufficient.
I am willing to correct my vote, but under a smooth installation I imagine something else.