Possible cd-rom drive error

After reading a post, I decided to run sfc /scannow on my vista machine just for fun. It started up and verified etc, no errors and went on with my day... My friend is having a lot of problems with his XP machine due to corrupt/missing files, so I decided to scan his machine. I noticed a few different things between the XP and Vista setup, for one on vista everything is ran in the DOS console, while XP calls a GUI when I run the scan. For some reason I need the windows XP cd while running the scan (but didn't need it for vista)

So I inserted the cd, and it told me that it was the wrong cd... to make sure I went ahead and booted from it... Since it booted just fine, my friend told me that I could just re-install windows, because he had no "valuable" information on the computer...

The cd booted just fine and ran until just past loading the partition manager, then said it couldn't find a file. I restarted the machine and tried again, this time it stopped even earlier saying it couldn't find a file... It is like the cd drive is getting to much work and shutting down, I can feel when it will stop working because it just stops spinning, then says it can't find a file...

So the question is, are there any ways around this? I have an external cd drive that connects via usb, is there any way I could configure it to try and boot via usb and just put the install cd in there? Any tips or suggestions to getting this machine able to re-install would be great, thank you.

Check the machine's memory..
I've had similar problems with a machine once..
Turned out the internal memory was b0rked..