That iMac will run Tiger or Leopard.
However, you will need to upgrade the memory. It is fairly inexpensive and I would suggest at least 1GB.
Here is a site
that I like a lot because they support Macs.
Choose your iMac from the list and then look at the options for memory. If you need help installing the memory, check with Apple Support
, or get your user manual out. The instructions are in there. It is easy, remove the bottom cover and clip the ram module into the slot. Make sure to seat it firmly, but not too firm. It should click down. Replace the bottom cover and start it up. Check with About This Mac under the Apple Menu to see if the install was successful. It should now read 1.25GB.
After you get the ram installed, then get a copy of Tiger or Leopard and install it as an upgrade.
After that you will be able to use the iPhone with no problems.
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