I have the 2 bay firmtek SATA enclosure for my macbook pro and I use the express 34 card to plug it into the macbook pro. Simply, I love it. The bare kit is $300 for the case and card. Go to newegg and get a few 500 gig drives for about 130.00 each, maybe cheaper and you are off and running. Getting a SATA card for a big mac, a G5 or a MacPro is about 100 bucks. It depends on what you want to do, I am looking for fast storage, I do it take it on the road and I do have more than 2 drives and I bought a few more bays. I love it, it is faster than firewire 800. You can't share the drives with everything but do you really need to? If you do, then getting a firewire 400/800 drive is for you. I had to take a look at my 6 lacie drives on my desk and I had enough. I have sold all but 2 lacie drives. Check out the theDamBook site, there is a forum section that deals with storage....
Best of luck.
Ken