Are you in the US right now?

I wonder because you said $1000 but are from belgium. In Europe you get two 22" 1080p screens for a total of 200€

RAM is cheap nowdays.. go for a 2x8GB or 2x16GB pack (i use 2x16GB in my rig, with slots for 2more)
16GB should keep Swapping to a minimum even with large files & multiple programs etc., DO get a SSD for OS & programs atleast, 120GB is the bare minimum but nowdays i wouldn't settle for less than a 250GB drive, samsungs 840 drives are superb in terms of price per GB/performance

If you think about GPU, i don't think you need to go THAT high end if you arn't going to do some insane rendering tasks.. used as a 3d modeling program you probably only want to keep the VRAM on the board high, 2-3GB should keep you without needing to swap even if you work with lots of textures with high resolution.
the circuit is probably less important to be honest because (I'm guessing now) she won't be modeling some ultra-highpolygon models with 2GB of textures on a detailed enviroment all at once. So i'd go from midrange->lower enthusiast models of GPU's that still hold up in the VRAM department, Swapping is what makes stuff feel sluggish.

In terms of prioritys i'd say:
SSD->RAM->VRAM for the responsiveness of the system, SSD for making loading go quick, RAM to keep the need for swapping when the programs are loaded to a bare minimum (the harddrive is still the bottleneck of the system)

As for CPU, an i5 - i7 cpu of the latest / last gen depending on how much of the budget that is left with a corresponding motherboard (CPU & RAM is more important for photoshop almost no photoshop plugins/addons run on the GPU, a thing to remember), check the RAM compability in the manual of the board though, if you want to be sure that it is going to work you usually have a list of certified modules in certan configs in the manual (there are times when 2 modules work, but when you go up to 4 you have problems, if you have alot of those notices in the manual, look for anothter motherboard)

uhm.. so.. yeah.. thats my thoughts.

just some background on me:
I work as a IT consultant (SMB to Enterprise) and have been building computers for friends and family since i was about 11..(28 now) worked with some media companies with picking out hardware for their workstations, though they did advanced rendering work so we had multi-gpu setups for them instead of more towards RAM & CPU.
Looking on how you describe what she is going to do i'd say you should lean more towards CPU/RAM than on the GPU.

1000 usd is a very tight budget for a graphic designing and gaming desktop with 2 screens. I recommend reddit/buildapc and PCPartPicker sites for recommendations.

I'm in Belgium. So 1000 euros. The prices usually translate that way.

Thanks for the good advices.  Her teachers toldn her last year that more than 2x8GB ram would end up being useless, so I'm thinking skipping 2x16 and focusing on memory frequency.

She will still play a few games on the PC for the next 3-5 years, but according to your post a R9 270x or 280x might be enough for her work ? As far as rendering is concerned, it doesn't need to be faster than her current laptop, as she can use it while rendering and will probably not do that much short movies anymore.

Also your job is pretty much what I'm learning right now, though not anymore in university.

It's actually 1000 euros and second screen is optionnal in the worst case scenario.

budget too tight, I recommend making more money. You won't have much of a pc with that amount. But nvidia is better right now, no getting around that. Their cards are just much better when it comps to direct comparisons for compute performance.

Are you a french speaking or Dutch?

tweakers.net is a good start for you with up to date prices

http://tweakers.net/reviews/3681/4/desktop-bbg-september-2014-mainstreamgamesysteem.html

Unfortunately I'm french speaking and I'm dutch is terrible. I usually use LDLC to check the prices.