Up to now I have simply downloaded images directly from my camera to IPHOTO using a USB cable and then click YES when prompted to Delete Originals - thus clearing off the CF card in the camera.
Is there any advantage to purchasing a Card Reader?
Thanks.

There's a few but it's largely personal choice;

Some readers are simply faster--for example some of the firewire based readers are very fast and there's probably a fair few USBs that are probably quicker than your camera too

There's a certain amount of wear and tear connecting your camera to the computer, around the USB slot and the covers etc. A cheap USB reader can be had very cheaply indeed, far cheaper than a repair. Not to mention a big dangling cable being a tempting target for a cat/dog/child/wife which can result on camera on the floor (card reader on the floor is less serious)

Theoretically (not actually heard a case of this) if your computer is hit by a power spike (by a lightning strike somewhere downline for example) you camera could also be frazzled (so best not lose computer and camera).

Some readers can be daisy-chained so you can download multiple cards at once, quite nice when you have a stack of cards to deal with

Personally I don't like faffing about with cables so I leave a card reader more or less permanently connected to my desktop.

Probably many more choices, but if none of those worry you, keep using the camera.

C

card-readers are quicker to download.

Also, doesn't drain your camera battery, especially if you have a habit of forgetting to turn off the camera after transferring...

I use multiple cards but for backup and redundancy purposes - always anticipate errors. And it's just easier to use a reader.

Also, it's easier even if I only have one card to read - and the card readers are cheap.

good for firmware updates too
Reader all the way
Its just easier and faster less hassle

OK I'm convinced - would welcome recommendations on which one to purchase for SanDisk CF cards

Do you have Firewire availability, or are you restricted to USB?

How fast are your Sandisk cards (ie II, III, IV etc)? There's little point buying a super fast firewire reader if your card cannot physically transfer the data..... Although if you're thinking of upgrading your cads, that's a different story.

Even a basic USB reader is usually fast enough for the slower cards...

Right now my La Cie backup drive is connected to a firewire port - so I could temporarily disconnect the La Cie and use firewire.
My cards are all SanDisk Ultra II
Speed isn't as important as reliability to me - I don't shoot enough and I have plenty of time

Just about any reader should be faster than an Ultra 2.

EBH

How about this one: http://www.bestbuy.com/site/SanDisk+-+ImageMate+All-in-One+USB+2.0+Reader/9032361.p?id=1218013808287&skuId=9032361&st=sddr-189-A20&cp=1&lp=1

SanDisk has a Firewire 800 that supports udma. It's quick downloading but CF only. I use 300x or 600x CF so it works well for me. Have a Delkin multi-card that works for the SDHC cards that I use as secondary on the D300s. It supports UDMA CF but is USB and doesn't download the RAW files as quickly as the SanDisk.

Mike,
Does it make sense for me to get a Firewire 800 reader to use with my Ultra 2 CF cards?

If you plan to move to faster cards down the road, I would. Here is a link to the SanDisk...
http://www.bhphotovideo.com/c/product/446772-REG/SanDisk_SDDRX4_CF_901_Extreme_FireWire_CompactFlash_Card.html

You can get less pricey readers that would be fine with the Ultra 2 cards. I switched to 16 GB cards and tend to load them up before importing them from the card. The faster cards and reader saves me a little time over the USB reader.

USB 2.0 or FW400 should be plenty fast enough for Ultra II cards IMO. I use a USB 2.0 reader (the Delkin eFilm, which cost me under $20). Just make sure it's UDMA capable.

What does UDMA mean

Here is a brief description of UDMA pertaining to compact flash...
http://dpnow.com/4445.html

Here are some tests results of newer UDMA cards and readers... For me, the card to PC download speed is most important. Might not be for you.

http://www.robgalbraith.com/bins/content_page.asp?cid=7-10044-10297

As stated in first link, if your camera doesn't support UDMA, don't waste your money expecting faster write performance in your camera. If you don't shoot large RAW files and load lot's of files on your CF before downloading, or you don't mind waiting a little longer, go with less expensive cards and readers. For me, I am more concerned with not sitting in front of my Mac any longer than I have to, waiting on my pictures to import before I start picking keepers and doing any processing I might want to do. That's my main reason for buying faster cards and reader. Am I wasting money I might not need to... probably as I do this for fun, not $.

If you sometimes dont take spare memory cards with you for say maybe a quick sunset shoot or something, I have foolishly left my memory card in the card reader numerous times...