Yea, there are only about 2 or 3 upgrades on iMacs.
- First the RAM. Upgrading that to the max will cost ($75-100 per 1GB stick) or so depending on what you already have. That mod you can do yourself and save a ton of money. Apple charges a load for RAM.
- A new HD will cost $100 or so depending on how many GB you need or want. That should be done at the Apple store for two reasons. First, if you take apart your Mac, you will void the warranty if you still have one. Secondly, I bet its a more difficult mod.
- A new optical drive. If you have only a combo drive you can get a dvd burner installed I assume. If you've got the burner, then you're good to go.
Bryan
To really help you, we need to know your computer's specs.