Bad Windows 7 DVD

[unix]

I bought a set of Windows 7  DVDs  off Ebay 6 months ago.  It came with 32 bit and 64 bit disks.  The disks were sealed. Not used. The 64 bit disk is apparently bad, it has two scratches on it and cannot be installed and is not even visible when mounted. The DVD drive just tries read it with wild noises to no avail.

I was forced to install the 32 bit version on a 64 bit machine. Question, does this hurt performance, and what real world difference is there?

Can I contact MS and return this 64 bit disk to them  so they send me another one? 

[DarkHumour]

The performance differences may be negligible but 32 bit o/s can only address 4 GB of RAM.

For replacement media

http://support.microsoft.com/kb/326246

[benali72]

I had a bad (defective) Windows CD from MS once, they replaced it without any issues when I sent it to them.

[unix]

I have 4GB and it's recognizing only 2.5GB, a well known bug, or "feature".

Thanks for the feedback.