Make backups fast, it can fail anytime. My HDD completely jammed when it started clicking. Everyhting was gone.
hmm... Mine is making a funny noise (not clicking, but it sounds like it's spinning off balance maybe? i don't know) I don't have anything important on here that can't be replaced (games that I have the disk for, downloaded files). Unfortunately, I don't have alot of money, how much would a new (fast, big, fast) HDD cost? I've heard good things about something called a "Raptor Drive." What's that (specs) and how much does it cost? Thanks.
If you are afraid of losing data, you may want to look into RAID1. Many mobos support it these days. It mirrors the disks, so you have two with identical content. If one fails, you still have the other. Has saved my ass a few times.
And always make external backups zip drives, tape drives, CD, DVD, removable HDDs. I had a power spike once hit a RAID1 machine and both disks where toast. Luckily I did have backups on another machine though.