Should be OK:
Almost all pre-built PC's (desktop and laptop) have a BACKUP IMAGE of the Windows OS on a hidden partition.
You can RESTORE this hidden partition usually two ways:
1) Boot disc
2) F-Key (such as F10)
Both options likely still exist. The easiest one would be to initiate with the appropriate F-Key. You can try experimenting on bootup to see what pops up, then look for "FACTORY RESTORE" or whatever. You could also try looking at the Gateway Support site.
*You may have wiped out the Windows installation, but I doubt you wiped out the backup.