Hold the low level format for a minute. You guys missed something: Araknis, you stated the BIOS update was for the MOTHERBOARD: "When I downloaded a bios for my computer it no longer worked." Therefore the 500 GB drive is NOT likely to be the problem.
Since the error occurred with the BIOS update, you should be able to return to the previous version. These BIOS files should be at the motherboard makers site. The newest one you tried may be a bit too beta and you didn't know it OR you somehow got an old or damaged one. Either way, I suspect it likely this BIOS version wasn't bug checked for drive size restrictions.
Now, if possible, try the drive on another SATA compatible PC which recognizes the drive at full capacity. If it boots as master, you'll be asked for drivers and all that... just shut it down. This will confirm if the drive itself is the problem or the BIOS update. If you have data to retrieve, set as slave and copy it all off before using further drastic measures. Then go back to the original PC to apply the fix.
The fix if the drive is OK: Re-flash the mobo BIOS with the last/previous stable version OR the one you had to begin with (if you can recall it). Don't be too surprised if you have to try more than one BIOS file to get the right one. I know this will be tricky as you most likely did the 1st BIOS update from Windoze on the 500 GB drive. There are 2 options: 1) You'll have to setup a DOS boot floppy disk on another PC, copy all the files to it, boot, run the flash program and swap the BIOS files (you may be lucky and find there is a "bootable floppy maker" BIOS update file at the mobo site to do all that with less fuss). Make sure it's a good, fresh formatted floppy and there are no disk errors. 2) Alternately for the non-command line literate, install Windoze to any smaller drive (SATA or IDE) the mobo supports, do the BIOS update fix on the 30 day OS trial without installing any extraneous drivers, shut down and reinstall the 500 GB drive to see if it's all Jake. Your drive should show up and boot if it is.