When do I need a new hard drive?

If you need more memory get an external hard drive. 5 years old is not that old. i have a computer that's almost 10 years old, i use it for more than 12 hours a day (on average). And the hard disk is fine. As long as you take care of it like you don't power it off while there's a disk activity..etc it should work fine.

But since you need more memory get an external hard drive.

A new hdd would be good to have increases your virtual memory as well , also shows faster boot time , and access to programs easier, drives don't really fail in five years any time a hdd can fail , the only way to tell is always have the SMART enable in the bios a early warning system for hdd's

When you hear a lot of clicking noise from your hard disk and when your file takes extra longer to be opened.

First you should get an external hard drive and back up all your data just in case your existing hard drive died.

Better be safe than sorry

Yes hard drives eventually fail and yours is 5 years old now so get a new one and back all your data up on the new one. You can still use your old one until it dies though. No sense in wasting a good HDD lol

Not nuff info.

How big is the HDD?

Do you have an external HDD as backup?

Use the old HDD as long as possible.

RAM ya kin stick in anytime IF yer PC allows it.