Yes, I second the graphics card on being important here for the graphic design work. With Adobe Photoshop you'll end up needing the extra space for scratch disks, but if you can get a system with a high amount of DDR3 or DDR4 ram on it, you can shift the majority of what you need for the graphics editing to ram, and then page the rest to the hard drive in a scratch disk file.
You'll have a lot of space to do that with on a 1TB hard drive, but the magnetic hard drives are really slow by comparison, and you'll start to feel it without defragmenting often with a 5400rpm laptop drive (or even a 7200rpm drive under stress).
The price of magnetic drives are getting cheaper more quickly than the price of SSDs, though. I just got an 8TB external drive (magnetic) for storage for about $198 the other day, so if you need a ton of space to store or consolidate one or more external drives, then there's still a use and a purpose there with the magnetic drives. You get a whole lot of space for way less money if you only need to access it once in a while, and you don't carry the drive around with you. If it's that type of arrangement, you can get a huge external drive for cheap now. However, if you want a faster system today with plenty of space until the day you can get a 1TB SSD drive, then I would just get an SSD for your main system instead.
The prices on SSD drives are gradually starting to come down this year where you can get a 480GB drive for under $100. Personally, if it were me I would just go with the 250GB SSD drive, and then image the drive to a 640GB drive or higher later. By the time you've filled up the 250GB drive (even if you're doing a lot of daily design work with it and saving finished files to the drive along with the temp space), you'll likely be able to get a 1TB SSD for nearly the same price as a 480GB SSD today to replace it with and copy everything to that.
You'll be able to convert your 250GB SSD drive into an external drive with an enclosure for about $25 or $30 too, and that way have a smaller but shock-resistant external drive backup of your works and be able to use that in a pinch if you ever need it but without any slowdown like you'd have with the larger >1TB external drives.
Ideally, you'll probably want to change out all your magnetic drives to SSDs over time when you can afford to. Right now, we're in the inbetween stage with the industry, so the magnetic drives are competing for largest space for the lowest dollar amount, while SSD drives are competing for the fastest speed at the best all-around price.
I would make use of any magnetic drives you have for cheap now if you've already bought them and use those as backups for your backups maybe, but it makes sense to gradually migrate everything over to one or more SSD drives for faster use and productivity in the future.
Once you use an SSD rather than a magnetic drive, you'll start to appreciate the speed and advantages of it to where you wouldn't want to go back to a magnetic drive again if you had the choice.
No more defragmenting and most bottlenecks disappear when you don't have to worry about moving parts anymore.
