Do the Aluminum iMac models have PCI slots or expansion bays?

No. The Aluminum iMac models were designed to be simple, compact, and relatively inexpensive, and consequently, there are no PCI slots or expansion bays.

If expansion is a top priority, and cost is a factor, you would likely be better served with a used model from the Mac Pro, Power Macintosh G4 or G5 series.

Site sponsor Operator Headgap Systems specializes in heavily upgraded expandable systems with an eye on both backwards-compatibility and the future.

What are the capabilities of the optical drive provided by the Aluminum iMac models?

All Aluminum iMac models have a slot-loading 8X dual-layer "SuperDrive" -- capable of burning double-layer DVDs at 4X and single-layer DVDs at 8X. The drive can burn CD-R at 24X and CD-RW at 16X as well.

Do the Aluminum iMac models support dual displays? What is the maximum resolution for an external display?

All Aluminum iMac models support dual displays.

Apple reports that the "Original" and "Early 2008" Aluminum iMac models are capable of supporting digital resolutions up to 1920x1200 and analog resolutions up to 2045x1536 on an external display while simultaneously driving the internal display at its native resolution.

The "Early 2009" and "Late 2009" Aluminum iMac models are capable of simultaneously driving the internal display and up-to a 30-inch external display (2560x1600).

Do the Aluminum iMac models support 802.11n?

Yes. Apple's specifications formally note that the systems provide "built-in AirPort Extreme wireless networking (802.11n)."

For the wireless capabilities of all "recent" -- G3 and later -- Macs, please refer to the AirPort Capability listing.

Also see: What is is 802.11n? How is it different from 802.11b, 802.11g, and 802.11a?