Is digitalrivercontent.net windows iso legit to download? Or is there an alternative and safe source?

Hi! I have windows 7 professional retail disc with both the x86 and x64 discs that came in the box., not downloaded  My computer started getting strange in the last few days so I decided to just back up my files and do a clean reinstall.  I used to do this all the time with XP and never had a problem.  For some reason I keep getting error messages when I attempt to install Win7x64.  I have tried to install it 6 times now. About half the time it says that some installation files are corrupt or missing. 

Its driving me nuts, especially since these are the same discs that I originally used to install windows on my computer before. I can't help but wonder if the discs have degraded or something.  I can't imagine how though because they have been sitting in their case in my closet since I last used them. 

I found some links to some windows iso listed on some webites called digitalriver.net and was wondering if they are authentic iso images.  I don't want to use some hacked/slipstreamed iso files. Also I don't really want to do anything that is not legit.  I read that digitalriver.com is a MS partner or something but I noticed these links are to digitalriver.net Is that some kind of trick to get people to download something bad?

If these files are not trustworthy then is there any legit recourse I can take in getting a proper windows 7 x64 iso that I can use my key with?

Thanks in advance!  This is so frustrating... how can it be that LInux is easier to install than windows? What is this world coming to?!?