iMac memory

[Grod13]

What is the main difference between replacing the internal memory (HD) and just adding an external memory?

[EricNau]

I assume you're referring to Hard Drive storage?

An internal drive will be faster, but the difference should be nominal (especially if you buy a firewire external HD). Plus, adding an external drive is far simpler.

Does this answer your question? If you have any additional, more specific questions, feel free to ask. :)