To be frank, I'm not too sure what she needs as such but I can see that multiple cores will come in handy so long as the apps that she uses takes advantage of them. My point is more to do with spending money on things that won't make a difference performance wise like the motherboard or spending a certain amount on a component when something better can be had for similar money (case in point, Q6600 vs Phenom II X4 940).
I would say that the E5200, Gigabyte P31 and 4GB approach would be best value. Clock for clock, the E5200 should be about 25% quicker than the Athlon 64, a tad less or more depending on how much the Socket 754 single channel memory controller hits performance, then factor in a 100MHz clockspeed benefit and a second core. Should make a significant difference so long as you can confirm that the applications that she uses are multithreaded.