For netbooks you have some very limited picks. You can remove the drive, place it as a second drive in a working XP system, copy the files over. This may fix things for now, but the error happens often when the hard drive is failing. So you need to check the BIOS of your system for a disk check utility and do a scan of the drive. Not checkdsk from Windows, a full hardware drive scan.
The issue then becomes if you replace the drive, you loose access to the restore partition which is probably on the old hard-drive, so you need to either get an external CD drive to load Windows on the new disk, or make a USB flash drive setup of XP.
You can also contact Gateway, they will be able to ship you a replacement drive with a restore partiton on it already if the system is in warranty.
If you don't care to save any files/favorites on the drive now, you can use the restore partition and bring the system back to factory settings. The documentation that came with your computer will have the steps on how to do that. You may not have a resotre partition, but I doubt you don't, you'd need one to restore the system without an optical drive.