I work in 3D Applications on a daily basis. If she is going to be doing just 2D graphics design such as Photoshop work, then there isn't a need to get a workstation graphics card such as the the Quadro FX line. It also depends on what 3D app she'll be using. Maya's workflow is dependent not only CPU intense operations, but also int he viewports your graphics card plays a big roll on how many polygonal faces/verteces you can display at once. Also rendering is all pretty much CPU driven with limits on large scenes in regards to system memory. 3DStudio Max is also similar to Maya as far as it's hardware functionality goes. Lightwave/Houdini are both pretty much CPU driven and don't benifit much if at all from a workstation graphics card.
For starting out however, she's not going to be needing the best of the best. For a starting 3D Graphics system, you could easily get by with throwing in a single Opteron 140 series, at least 1gb of ram, and a GeForce FX 5900. I wouldn't recommend going with ATI cards at all with 3D apps as they don't deal well with them, they have a lot of known issues with the big 3 (Maya, Max, XSI).
I have a Quadro FX 3000 card in my system and there are times when I push it to it's limits, but I work with scenes with 3,000,000+ polys which isn't something she'll be doing for quite some time and there is absolutely no reason for her to spend that kind of money.
It all really depends on her budget, spending over $4,000 on a 3D workstation can easily be done very quickly, but for someone who is just getting into it, there's no reason to spend that much. Get a somewhat decent machine now, save up till later when she'll know what she'll be doing.
Emmortal