"I/O" stands for Input/Output, so an "I/O Device" is the Input/Output device you happen to be using at the time. An "I/O Device error" means that some kind of unrecoverable error happened on that device. Which would suggest that perhaps your new hard-drive might be faulty. You could run a couple of test on the hard-drive.
Something like this: Disk info. or this: Acronis. There are others but I'm am on the iPad at the moment so when I get to my desktop I'll have a look for others. But these should give you a fair idea on the state of your new HDD. Although Windows 7 comes with many generic drivers it is always best to install the ones from your laptop maker.