SMART Codes are hard drive Firmware Warning Error codes, that usually signify that a hard drive failure possible, due to high disk error rates, or other issues.
If the Dell is still under warranty, and/or the Hard drive is still under manufacture warranty, I would try to get a replacement as soon as possible. Somtimes there is a 3-5 year warranty on the hard drive, even when the computer has only a 1 year. So it pays to check with the hard drive manufacturer.
Many of them will replace a hard drive giving a SMART code. Even if the drive has not completely failed yet.
What ever you do, make sure you back up everything quickly. I sugguest you do a full image of the hard drive, using Ghost, or R-IMAGE, or some simular program. That way, you can restore the to the replacement drive and be running quickly if you get them to replace it.