Generally, any USB keyboard will work on a Mac. You can even use the USB one from your PC, although the modifier keys are not in the right order. In that instance, you might need to "remap" them with a utility program.

Since these modifier keys are so important to becoming an efficient Mac user, I would suggest getting a keyboard made for Macs rather than re-using your PC keyboard. There are many manufacturers (even Microsoft) that make them with the extra bells and whistles that Apple's streamlined keyboards seem to leave out.

I've read of hooking one Mac up to another in "Target Disk Mode". What does this mean?

Target Disk Mode is a way to connect one Mac to another and have the "target" function solely as an external hard drive. You can't operate the target Mac at all in this mode. It just shows up on the the master Mac's desktop as another hard drive.

To use Target Disk Mode, you connect the to Macs directly with a FireWire cable. You can do this all with the master Mac turned on. Once connected, start the slave or target Mac up holding down the T key. In just a few seconds the slave will come up with the FireWire symbol on the csreen and a new drive will show up on the master's desktop.

Why would you want to do this? Here's a couple reasons:
First, it's a great way to transfer files and settings when upgrading from one Mac to another. Migration Assistant will ask you to hook the old one and new one together and then it copies the data it needs over to the new Mac.

Second, It's a very fast way to transfer large amounts of data. Normally I use my wireless network or a flash drive to transfer files, but when the transfer gets over 2-3 GBs, I will connect via Target Disk Mode because the connection is faster and I don't have to duplicate the effort.

Lastly, you can use this to get by some permissions that might prevent you from reading files when the target Mac is connected normally. Shhh…

Absolutely! I highly recommend using more than 1 monitor when ever it makes sense. The Mac OS has been able to add a second monitor "out of the box" for more years than I can recall.

Mac Pros come with two monitor ports and the other Macs (other than the Mac Mini) have an extra mini DVI port to add an extra monitor. You just need to buy the adapter to hook up to a regular DVI LCD monitor. Even iMacs have them. You configure them in the Displays preference pane in System Preferences. It's a great way to use a small laptop like a MacBook and still have a large monitor, using the MacBook's screen as the secondary display.

I believe you can never have too much screen real estate, even with Leopard's Spaces for two reasons:

First, the Mac rewards you experimenting with dragging and dropping files, bits of text and more from window to window. You need the space to have multiple windows open to do this easily.

Secondly, many programs these days have a bunch of accessory tool palettes to get the most out of the program. For instance, I use Photoshop with my main 24" LCD hosting the image file, Layer Palette and Tool Palette. My secondary 20" display hosts another 9 palettes plus iChat off in the corner.

With non-Apple displays getting cheaper by the minute and Apple making it so easy to do, I strongly encourage using dual displays.