firewire audio interface

[ghosthorse]

(i'm pretty sure there have been thousands of similar threads.. i'm sorry for that..)

hello,
i'm searching for a firewire interface.

what i want to do:
plug in a guitar (or whatever) in any input, send the signal through a vst plugin, and then to an output, which i can freely choice. (and then in a seperate mixer)
(and i also wanna do that with vocals and two other instruments, at the same time)

it should have at least 4 inputs, at least two mic-preamps, hi-z inputs would also be great (or is it not that important, could i also do guitar, bass etc through line-inputs?).
i think, i need at least eight outputs.
adat would be great, though it isn't that important.

because of the vst-plugins i will need a low latency.

my favourites at the moment are:
focusrite saffire pro (but it looks like routing possibilities are very limited),
echo audiofire 8,
motu ultralite.

currently i'm using windows xp, but in the future i will go with a macintosh.

which interface will do the best job for me? it should be in the same price range as the three listed above.
does anyone have expieriences with the saffire pro (routing)?
i think i don't have enough money for a rme..

i hope:
that i didn't forget anything,
that you will help me,
that my english isn't too bad.

regards!