I'm a Hitachi and Samsung fan, but I do have one WD disk in my PC, which is the oldest disk I currently have and 320GB in capacity. It's been flawless for years. When it comes to hard disks, they're all pretty good these days, but you'll find enthusiasts' opinions differ as to who is best as much as the sports teams they follow. lol.
If it was me, I would wait a little longer if possible, and purchase a new disk. It might be cheaper to purchase a new disk and then a separate enclosure for it. You're taking a risk with a second-hand disk; you don't know its history, whether its been damaged, dropped, how much its been used, if it has any errors and more crucially, it won't have a warranty.
Now it might last ten years, or it might be unreliable in a matter of days or weeks.
How big is your hard disk now, and could you realistically reduce its size by removing stuff you're not using right now, or infrequently use? Pictures for example can be backed up to removable media like DVD-R's which could be especially handy for pictures you're storing but not accessing regularly.
Edit: If it makes any difference... I use Hitachi in servers or other disk intensive file-serving roles because in my mind they're just more rugged for that sort of usage. For my media on my main desktop, I entrust it to Samsung's SpinPoint 1TB F3's and 2TB F4's. My first disk is an SSD, but if it were mechanical it would only be Hitachi. Network backups or disk storage I go for Hitachi. I only have the WD in my main PC because I wanted a separate disk for VMs and had it laying around. I'll likely be throwing in a 500GB+ Hitachi shortly as its getting rather full now. lol.