Stuck between external drive choices

I'm heading off to college in about 6 weeks and I'm trying to get all my tech purchases done now. I've got a macbook pro in the mail and I need an external drive for backups/more than the 250 gigs it has. Problem is, I have a 500 gig internal drive in this computer right now, and it's at 340 gigs filled (although I'm sure I can lose 100-200 gigs or so by removing random crap I have for no reason); and the drive must be from Best Buy since loans are expensive and I have a $120 gift card there. Suggest a better drive for me if you can find one but all I've found so far is these 2:

Western Digital - My Book Essential 1TB External Hard Drive
1TB (obviously)
USB 2.0 only

Western Digital - My Book Studio 500GB External Hard Drive
500GB (obviously, again)
Firewire 400/800 and USB 2.0
Matches laptop

I can't decide if I'd rather have the 1TB since I'm already in the mid 300GBs, or if the 500GB is better because of firewire 800. The laptop only has 2 USB ports, one of which might be home to my wireless mouse receiver unless it keeps acting up, and it'd be nice to have at least 1 free usb but I'm not sure the price of 500 GB is worth it

go to bestbuy, sell your gift card to someone in line for $100. Stand right in line with them so they know they aren't getting scewed- then take your money and buy a external hdd off of newegg thats twice as large as one from bestbuy.

Actually better yet- buy an enclosure w/ firewire and put the hdd in yourself. Usually cheaper.

Assuming you could sell off that gift card to someone and get the money back. You could use it to purchase this WD drive, a fellow OCF'er recommended to it me here and I have it solely for storage purchases which I believe is what you're aiming for:

http://www.newegg.com/Product/Product.aspx?Item=N82E16822136218

and install it into an enclosure that supports over 500GB. There's a post that's mentioned the Antec MX-1 as a great enclosure. The recent updated review from SilentPC (June '08?) notes some increases in fan noise. Here's the thread:

http://www.ocforums.com/showthread.php?t=570180

it might seem slightly on the larger side if you frequently travel around with it. I can't find the one that features USB only, but you'll save quite a few without having a use for the eSATA (does the MBP have an eSATA port?).

However, I can understand if you do wish to purchase one from BestBuy to use that gift card, I'd go for the 1TB for the price... you'll spend around $70 only with the additional $60 instant-savings.