I also find this is an overkill system, but based on your suggestions.
CPU: Intel i7 920
RAM:
G.Skill DDR3-1333 3x2gb
Case: Antec 1200
DVD:
LG GH22LS40 I guess as a DJ Lightscribe might come in handy.
Motherboard:
Gigabyte EX58-UD3R The i7 compatible mobos are really pricy.
GPU:
Sapphire Radeon HD4890 Vapor-X It is pricy, but its quiet. It is also quite overkill.
Monitor:
Samsung 245T Its a PVA, she could also get a cheaper
Samsung T240
PSU:
Antec CP-850 Once more it is overkill, but its modular and a great deal for the price. It only fits in a few cases, the Antec 1200 is one of them. Also, its pretty quiet.
Sound Card: I am not knowledgeable about these.
You could get something cheaper by changing those components:
CPU:
AMD Phenom II X4 955
RAM:
G.Skill DDR3-1333 2x2gb
Motherboard:
Gigabyte GA-MA770-UD3