Well... getting it checked if you're worried is always good, although my G5 came with a Maxtor drive (250GB model, though), whis is a lot noisier than most modern drives, and I would indeed describe the noise as a 'staticy radio station' -- that's just the head seeking. If you've used older computers, you're probably familiar with the sort of grinding or cricket sounds hard drives can make (depending on the age, brand, and acoustics of the case), and you'd recognize your current sound as a similar sort of noise.
You might try a couple of things: Open up Disk Utility and see what brand it is; if it's Maxtor, it might just be loud. You can also check the SMART verification from there--it shows up at the bottom of the screen when you have the drive selected, or you can use the little info button. (And if it says "Not supported" under the SMART section, just re-launch Disk Utility--it sometimes seems to get confused, and that always seems to fix it for me.)
For comparison, I added a Hitachi drive to my G5 and made the Maxtor the backup slave (I don't trust Maxtor drives with important data), and I can only hear the Hitachi if I listen very closely. The Maxtor, on the other hand, is quite audible any time I'm doing stuff on it. My recent experience with Seagate and Western Digital drives is similar--that Maxtor makes far more noise than any of them.
