To completely remove Win XP and install 7: back up any important data, then boot from the Win 7 install disk, and when you get to the step to select a partition, unpartition all partitions that exist on the drive, which will delete everything, and install on the unpartitioned space. Allocate all available space to the partition that Win 7 creates and allow it to format the space. Win 7 will then install and boot up.
You may need to select Custom instal to remove the partitions.
Also, you will need to go to the Manuf website and down load needed drivers.
Windows 7 does a pretty good job of installing generic drivers.