The two tower Apple Mac Pro models pack a brand-new processor and video system, and feature a reorganised internal design. However, they have lower clock speeds than their predecessors.

Last year's standard Apple Mac Pro featured a 2.8GHz eight-core Intel Xeon processor based on the Harpertown/Penryn architecture. This year, there are two models: a quad-core system with a 2.66GHz Nehalem Xeon processor, and an eight-core model running two quad-core Xeon processors at 2.26GHz.

Also new to the Apple Mac Pros are nVidia GeForce GT 120 graphics cards and a revamped interior designed to ease user access for upgrading internal components.

Apple Mac Pro: similar but different

Aside from the second optical-drive slot on the front, the Apple Mac Pro continues to use the same big-handled, aluminum case as the Power Mac G5, introduced nearly five years ago. There are some minor changes to the exterior, though - specifically in the type and number of connections.

First, the two FireWire 400 connectors from previous generations have been replaced with backward-compatible FireWire 800 ports, bringing the number of FireWire ports to four - two on the front and two on the back. The five USB 2.0 ports, two on the front and three on the back, remain.

On the graphics card, one of the two dual-link DVI connectors at the rear of the system has been replaced with a Mini DisplayPort connector, which lets you connect either to Apple's 24in LED Cinema Display or, with adaptors (not included), to a second DVI display.

The new Apple Mac Pros have been remodeled on the inside to provide for easier access to components.

Upon opening the Apple Mac Pro's case, you immediately notice major changes in the layout of the components. The memory modules are no longer installed on two sliding trays - instead, the memory and processor all rest on a sled at the bottom of the case, which you remove by releasing two latches.

The quad-core Apple Mac Pro has four memory slots that ship with 3GB, 6GB, or 8GB of 1,066MHz DDR3 SDRAM modules; the eight-core Mac Pro has eight DIMM slots for a maximum of 32GB of RAM. The memory design no longer requires the large heat sinks.

The Apple Mac Pro still has four internal cable-free hard-drive slots, using a sliding tray to attach the drives directly to the motherboard. Now, though, the large plastic piece holding the fan near the front of the Mac Pro is much smaller, giving your fingers more room to grip the hard-drive sleds.

This is a small but welcome change. We can't tell you how many times we've struggled over the years to remove that first drive. Another nice design change helps ease the removal of PCI cards from the four full-size PCI Express 2.0 card slots. In the past, to remove a card, you'd first needed to turn two large thumbscrews that held a small plate keeping the cards in place.

Then you had to feel around behind the card, searching for a little plastic tab mounted on the motherboard, which you needed to lift up in order to release the card. With the new Mac Pro, that second step is much easier. You now simply push a single thin bar that extends across all the PCI Express 2.0 slots to release any or all cards. Apple has also made installation of its add-on Apple RAID card much easier: you just put it into the clearly marked top slot, and you're ready to go.

Installed in the first PCI Express 2.0 slot is the new Nvidia GeForce GT 120 graphics card with 512MB of video RAM; the last generation of Apple Mac Pros came standard with an ATI Radeon HD 2600 XT graphics card with 256MB of memory.