How long should chkdsk take on a 500GB drive? Can't run backup

I ran chkdsk /f on my Win7 x64 computer and it took about 5 minutes on my 500GD WD Caviar SE storage drive. It said it corrected errors in the Master File Table (MFT).

Then I ran chkdsk /r and it got to stage 4 of 5 where it sat at 10% for over 24 hours. I think it increased in sectors or files scanned by a few digits during the time. I ended up cancelling the operation.

On a different computer, with a 500GB backup drive. I ran chkdsk /r and it took around two hours to complete. But that was a Win 8.1 computer (which also shows the Chkdsk "ETA to complete", which is nice).

So should I replace the backup hard drive (the WD Caviar SE) since it is taking so long to run chkdsk /r? Does this extremely long run time mean there is a lot of damage on the drive.

The reason I started Chkdsk is because I can't run the Windows backup program. It keeps failing with a Error Code 0x8078012D and also says I/O device error 0x8007045D.

Up to you Bumkin, greens are good for backup drives (they will power down when no activity), blues are silent and fast performing, blacks are long warranty and fast. All HDDs are backward compatible with all 3 SATA specifications as far as I know. There should even be a jumper setting to force the drive to work at SATAI speeds (1.5Gbps).

Thanks for the feedback.
I have a bunch of Seagate 1TB ES.2 drives left over from my RAID upgrade so I'll swap in one of those.