Why 4 Horcruxes left, and not 3??

[chrusotoxos]

No: HPFGUIDX 142086

Hi everybody...there's something bothering me about this story of 
Horcruxes.

If I remember it well, according to Dumbledore Voldemort made 7 
Horcruxes (let's suppose, for simplicity's sake, that he had already 
his 7 before murdering the Potters - it doesn't change my problem).
So Voldie has split his soul in 7 parts:
1) a part of soul in himself
2) Nagini
3) the ring
4) the diary
5) Slytherin's locket
6) something of Ravenclaw/Hufflepuff
7) Hufflepuff's cup

Ok, so here is my question: the night the Potter died, Voldemort got 
an Avada Kedavra curse (the one that rebounded) but he didn't die 
because his soul was not only in his body, but had been split in 
different objects. So that night, as I understand the whole business, 
his body died along with the piece of soul inside it, but as there 
were 6 other pieces safe Voldemort was not destroyed.

This would be, IMO the logical view of the matter. 

But it isn't, because if it was, we would have a less Horcruxes left.

So my question is, if someone makes Horcruxes, does that mean that the 
soul inside him cannot be destroyed as long as the extern parts of his 
soul has been destroyed? Looks like it. A killing curse, therefore, 
has no effect upon a split soul, but only on a whole soul. But if this 
is right, why don't all the bad guys make one? Or even important good 
ones, without whom the war cannot be won?

I thought at first that the seven parts of the Voldemort's soul were 
all little Voldie, and that from each of them a new Voldemort could 
reborn if the 'true' one was killed (as in Godric's Hollow). But 
appearances point to something else: it seems that Horcruxes are 
different parts of soul, parts that the person won't be able to use 
again, the good parts of him.
Dumbledore agrees with this when he says that Voldemort grew less 
human with the passing years; JKR agrees when she says that we'll find 
out why Voldemort is so evil.

In this case though, what gain there is in destroying the good parts 
of Voldemort's soul? Voldemort is powerfully magic; surely a golem 
composed with the part of his soul he threw away because not evil 
enough could be interesting?

But at the same time, this cannot be right: the part of soul we saw, 
the diary Tom, was unpleasant and cruel; what did Voldemort lost for 
being separated from it? His memory of that period? His memory of what 
it was like to be sixteen?

Ok, I'll stop here with this rambling, I just wanted to know if 
someone has understood this piece of Dark magic.

bye

chrusotoxos