+1 for SSD. Manufacturers will overcharge for them, but you can always swap the hard drive out of any laptop. I swapped my laptop's 750GB HDD for a Samsung EVO 250GB for like, $130 I think. It was a little bit lower on Black Friday, maybe ~$20 less.
If you need lots of hard drive space like I do, you can swap out the optical drive for a second larger hard drive, and put the SSD in the normal hard drive slot. I bought a 2TB HDD off Newegg for like $120 on sale, and a HDD mounting bracket for the optical slot off eBay for $10. I even got an external optical enclosure and turned my old internal Bluray drive into an external USB 3.0 Bluray, lol.
You probably won't be able to put two hard drives into an Ultrabook, because most (if not all) of them don't have optical drives, to save space and weight.
However, if you're not storing huge amounts of stuff, a 250GB SSD would probably be fine. The speed boost far outweighs the space constraint, and if you have the budget, you could spend more on a 500GB SSD.
The SSD will add onto the cost of the laptop (unless the laptop comes with one, of course), but its well worth it in the end. If you can find a laptop that includes an SSD, even better, but they will be more expensive, so it may be cheaper to buy the SSD separately.
Boxing Day is probably the best time to pick up an SSD, as they'll be on sale. Watch out for the Memory Express 'smoke and mirrors' pricing though...they'll jack up the "regular" price by 30% to make it look like the "sale" price is ultra low.
Check out
http://ca.pcpartpicker.com for price history on various components, including SSD's.
Also, agree 100% with what ken0042 said. If you're looking at $1000 budget, make sure its got at
least an i5, if not an i7, plus at least 8GB of RAM, and of course, the SSD.
Keep in mind, most Core i5 CPU's in laptops these days are dual core, not quad like you may expect. Quad core i5's are more common in desktops, or at least they used to be. I have seen dual core i7 processors too, although they are much more rare. Nevertheless, make sure to research the processor thoroughly. Check out
https://www.cpubenchmark.net for processor benchmark scores and comparison charts.
Lastly, if you're not comfortable changing the hard drive yourself, don't worry, its very easy. You may have to take out a few screws or open the casing, depending on the laptop. But once you have it open, its literally just a matter of pulling the old drive out and sticking the new one in. If you still don't want to do it yourself, any tech-savvy CP'er could do it in 5 minutes.