Building External Hard Drive Please Help!

Try this:
http://www.hardwaregear.com/productdetails1.cfm?sku=CG-2U2ATAB&cats=&catid=131,319,322,312,315
I've been using this enclosure with a pair of Maxtor SATA 250 GB drives. The unit has built in fans, FW400, USB 2.0, and FW 800. It's lightining fast, and I like the fact that you can always upgrade the drives if I need more space.

 

You can use pretty much use any HD or enclosure, it really depends on your budget. I just bought this enclosure from http://www.cooldrives.com/ducooldrives.com. It is a bit pricey, but it has everything I need: USB 2.0 FW400/800 and it's RAID 0. I just popped in my 2 WD 300GB SATA Drives and now I have a very nice 600GB Storage unit!

 

I'd recommend this Icydock enclosure:



http://www.newegg.com/Product/Product.asp?Item=N82E16817198003

It works with an eSATA drive, which usually are very large in storage size. The enclosure is the best-looking one I've seen; furthermore, the way you install the HD is very unique and extremely simple.

It seems to be designed with mac users in mind.

 

Good quality enclosures are not cheap. The chipset quality is important so, if you want to built a good quality external HD (using a reputable HD), you'll end up saving $20 to $30, it's just not worth it, believe me. Get one from OWC. The Mercury Elite Pro Aluminum USB 2.0 + FW 400, 500GB, costs $249.99.
The unit is covered by a 2 year warranty + 3 year warranty for the HD (total of 5 years for the HD). They use Seagate HDs, check it out:

http://eshop.macsales.com/shop/firewire/1394/USB/EliteAL/400+USB2/