Hi,
Let me make sure I understand you. Is the 7 GB free space on your Windows partition? Or is it in a separate, empty partition? If the free space is on your Windows partition you need to take problemchild's advice. If you're using an NTFS Windows XP partition, the partitioning programs that come with Linux distros won't cut it. Get Partition Magic or a cheaper alternative like Paragon Partition Magic (google it) to resize your Windows partition.

ALSO. make sure you defragment your Windows partition before you resize it. Windows has the habit of scattering files around the hard drive. If you resize the partition without defragging you risk messing up your Windows installation.