Dell Latitude e5430 hard drive issue.

Stock on the laptop came windows 7, but because I got the laptop in July, I was eligible for the $14 windows 8 upgrade, and jumped at it. Well, I enjoyed it for a while, but the end result was me wanting to go back to windows 7. So I threw my restore disk in and went through the custom installation run-through (because I had already backed up my files to another disk) and was just going to format and re-partition the drive (I had it set up with two partitions, and was condensing it back down to one). Well I do all of that in the Windows 7 Setup and now its telling me that the partitions cannot have windows 7 installed on them - unsure why, I look around a few times on Google figure I would just try the windows 8 install disk and see what happens from there. When I pop that disk in, the hard drive no longer shows up in the list, nor does it in the windows 7 install disk. The BIOS still shows I have a 320 GB hard disk installed, and I tried changing the SATA configuration from RAID to AHCI and ATA and nothing made a difference. I have a warranty on the laptop, but I would really hate to have to send it to Dell to have them fix it unless they are going to replace the Hard Drive. Any ideas on solutions or what I should do at this point?