There are a couple of options. The manufacturer of your laptop should be able to provide you with disks to reload the operating system. Often to save a buck or two they will put a partition on your existing drive. So give them a call (even if its out of warranty). It also might be a good opportunity to upgrade the OS. You might talk to them about getting Windows 7 either from the OEM or from a retail store. Windows 7 works well on laptops.