Alright, what should I do for my Time Machine Solution?

[capitanbuzo]

So here is where I am at. I currently have a Mac Pro (mid 2009) and a Macbook Pro (Late 2007). The MP has the stock 640GB drive in it and the MBP has a 200GB drive in it. I was going to get an internal drive to back up the MP but I figure I would like to have a drive I can keep in a separate location and that is not in constant use. For the MBP, I plan on getting a uMBP in the future with either a 256GB SSD or a 500GB 7200RPM HDD.

So where is the question at? Well, as you all know, external HDD's are discounted greatly during Black Friday (or the week). I have a couple options right now. One, I could (try) to get two 1TB drives from staples or I could get a 2TB drive from Newegg. The 1TB drives would run $70/ea while the 2TB drive would be $150. Cost wise, they are fairly equal. Which would be the better option? On the one hand, I would have to partition the drive in half for TM but the downside would be that I would only have 1 drive so it is less redundant. On the other hand, I can get a new external drive (for the MBP) by the time I update the internal drives for my MP and just use the 2TB drive as a backup. Also, I keep fairly the same data on both machines so it would be either triple redundancy if I went with the 2TB drive or quadruple redundancy if I went with two 1TB drives. Also, if I go with the 2TB drive, I wouldn't have to get up at 4A.M. to go to staples for the drives. Sooooo, which set do you think would be right for me?