here is the disk needing replacement. It's 3.5", right?
So I'll look for:
Hitachi
7200rpm
SATA 3.0gbps
2TB
right?
Doesn't need to be a Hitachi, but under real world use the 2TB HGST drives are running the longest of any drives at Backblaze in their awesome disk failure statistics data.
https://www.backblaze.com/blog/hard-drive-reliability-stats-for-q2-2015/
As you go up in size, other brands fare a little better in larger sizes.
Another route to go would be to stick a sold state drive in there (SSD). Most are 2.5" but brackets can be bought that they'll sit in to make them the standard 3.5" drive size.
I highly recommend Samsung EVO SSDs for personal use but their prices have been climbing. The latest model SanDisk SSDs have also been faring well in reviews and are a bit cheaper.
They're more expensive than "spinny disks" as we are all calling the older tech at work now, but the performance gains are real.
If your 2TB drive was full, there's not many options for 2TB that aren't outrageously expensive in SSD tech yet, and 1TB runs a little over $300.
The spinny disk in 7200 RPM SATA will run less than $100.
As far as the OS goes, if the computer was bought from a major manufacturer they probably included a recovery disk or USB stick -- or they have one available to purchase for a modest cost, just fall and ask them how you get recovery media for the machine -- which will reinstall it right back to like it was day one, including the operating system and drivers specific for the machine and whatever junkware they add on.
Many people prefer to just download or acquire plain vanilla Windows OS media and then just typing in the license key which should be stuck on the machine somewhere. A "cleaner" installation. But then you have to go to the manufacturers website and get the various drivers for things like video cards, and any special hardware like extra buttons and lights on a laptop, etc. Not usually hard to do but time consuming.
