I'd have to figure you are going to use a laptop.
I like firewire so as to not overload the usb port which you will probably use for your soundcard.
Plan on a PCMCIA firewire card to attach the drive to the laptop.
http://www.newegg.com/app/ViewProductDesc....-104-311&depa=0
A few things to consider:
Sealed drives will run hotter and require a wall wart power supply and they are not upgradable when they fill up.
I like these drive enclosures because they have exceptional cooling, utilize internal power supplies and if, down the road, I want to upgrade I can.
http://www.pcmicrostore.com/PartDeta...x?q=p:10500976
As for drives, it really depends on how much space you want.
200g drives are pretty cheap if you look around.
I found these recently:
http://www.tigerdirect.com/applications/Se...=THD-2000JB%20P
Typically as they fill up I retire them as back up drives.
As for brands, you will hear stories from users concerning failures from pretty much all of them. Sooner or later they all will fail, electro/mechanical things always do if given enough time. Personally I like Maxtor, then WD and don't care for Acomdata. Most drives will meet our requirements but look for 7200 rpm or better.