Hi - that combo won't work. The enclosure is PATA, the drive is SATA.
I'd absolutely go with Seagate for a dependable HDD. Every brand has failures, but Seagate has a better rep than most.
Every enclosure has two interfaces - the 'internal' interface, which connects to the hard drive, and the 'external' interface, which connects to your computer.
Internal choices are PATA or SATA, and External are USB2, Firewire 400, Firewire 800, or eSATA (many brands have two or more external options). USB is the most common, and the only choice common to Macs and PC's, if that's important. Firewire is considerably faster for most uses, and most modern Macs have it, so it's a great choice to have.
I'd choose SATA and a combo USB2/Firewire for an enclosure, personally.
I have this IcyDock enclosure which is SATA internal, and both USB2 and Firewire400 external - with a SATA Seagate 750GB drive. The enclosure has a little sled that you screw the HDD into, and the sled just slides in and makes the connections in the enclosure. You can have multiple drives in different sleds, and use it like a giant floppy drive, if you like.
http://www.newegg.com/Product/Product.aspx?Item=N82E16817198012
A USB2-only enclosure is cheaper, but considerably less speedy/flexible, and if you're looking at Gigabyte+ drives, I'm assuming you're planning on moving big files, where speed is valuable. I'd urge you to pony up the extra $20 for adding Firewire.
As for a pocket-sized portable drive, I'm increasingly a fan of the Western Digital Passport 160/250/320 series. Good little drives, reasonably priced, attractive enclosure, and mine came with a really nice little neoprene case with a pocket for the USB cable on the outside, which makes a HUGE difference in keeping it all tidy. I got mine at Costco.