Thanks karlsnooks and madtownidiot,
The drive wasn't making much noise, it was more like everything was freezing for some time (and you could hear it humming slightly differently) but no significant noise, no. Chkdsk reported no additional bad clusters after I ran it in a couple of days.
I think I will just run on this drive until (if ever) situation gets out of control and if it does I will just replace it myself. A bit of out of pocket expense, but that's karma I'm afraid. Obviously, some regular backups will be needed.
What replacement would you recommend in the same price category (i.e. 50-60 pounds)?