Replacing HDD on 2007 17" iMac My iMac's HDD has died so I need to replace it. I don't just want to go like for like, does anyone know what the upper limits of the machine are?

I have a 1TB USB drive plugged in, so I'm assuming the BOIS can cope with up to a TB which is fine. What I'm more interested in is restrictions on the SATA version and buffer size.

I'm not well versed on the mechanics of a HDD, so forgive me if any of this sounds naive. I just want to get the most bang for my buck.

Any help would be greatly appreciated.

Rich
As seen in Apple Discussions your iMac has the SATA2 controller.

Also there are no limitations from the controller for the cache size of the HDD. 

So you may easily go for an 7200 SATA2 16MB/32MB cache

note: The last 17" iMac, was the late 2006 model which I assume thats what you have :)

edit: Even if your iMac is SATA 1, it wont have any compatibility problems. It will just perform as much as it can (1.5Gbps/s)

last edit: If you use this tool you can see successful user upgrades and benchmarks of various hard drives.