I was playing a game when it froze. I powered down the computer and restarted. It began to loop from the POST messages all the way to the XP splash screen, over and over. After a few times, I got a message saying :

"Pri Slave Hard Disk: S.M.A.R.T. Command Failed"

I went into BIOS settings and disabled SMART for this drive and rebooted, but it continued to loop until I got another message saying, "Reboot and Select proper Boot device
or Instert Boot Media in selected Boot device and press a key"

Does this mean that my hard drive is gone? I have about 20 gigs of stuff on there that I really need to save.

Sounds like it!!

If i was you i would take the HDD out put it in another pc and try to copy the data off before you try anything else!!

After this download Seatools and create a bootable disk and scan the HDD for errors. It might not be totally knackered but normally if S.M.A.R.T is telling you it is, it is!! Could just be the boot sector if you get your data off ok, try to do a repair with a Windows disk

Ok, thanks. I guess I'll have to get on buying a new disk right away then. -__-

try running chkdsk on it from your xp installation cd [recovery console...]
chkdsk /p
And then slave it and copy off. Or use a recovery cd to get a copy command going.