If it was me, I'd go with the AMD Athlon processors, because I've had three on 2 different PCs and one on my laptop and never had any issues with them, the only time I've had an Intel laptop and the thing died on me.
Although I prefer nVidia for Graphics cards, ATi are more or less the same and if you aren't a gamer it won't matter either way.
2 sticks of memory will be better than 4 due to the fact that you will have 2 free slots over the other. Although the memory is slightly slower than that of the 2nd PC.
I assume PC 2 is more expensive than PC 1?
End of the day it all balls down to what you want from your PC and either decision you go for will be right.