Going to build a killer system but know very little about videocards. Help needed

I'm going to build an i7 system when the chips and mobo's hit the
market. Probably going with the top of the line I7 "extreme edition"
and the Ausu x58 mobo. 6GB ram?

I've had dual 19" samsung LCD's hanging in front of me for the past 5
years and want something very similar except I'm going to upgrade to
DUAL 20+" LED based monitors. I want this set to look SWEET.

I also want to have a 3rd monitor (probably one of the left over
sammy's) so I can run my sling player on it. (same computer)

So, that's going to be 3 monitors off of one system. One super new
fast system.

Now my question: What video card/cards should I use? I'm an ATI guy
so I'd like to stick with ATI (or it's OEM's).

I see all the crossfire talk but really don't know much about it.

I'd like some suggestions as to how I could best achieve my 3 monitor
setup. My current 2 monitors today are configured in XP (will
probably stick with XP and possibly dual boot Vista). They are
configured as seperate monitors which I can move the mouse between.
This way I can open programs and drag them (or have them open
natively) on a particular LCD. WEB of the left, email, spreadsheet,
word on the right (you get the idea). I had a few utilities that
allowed both monitors to act as one big space but then you are always
sizing your applications to a single monitor. I like the seperate
monitor config.

Oh, mostly work applications, a fair amount of picture / website
deisgn (photoship, indesign etc) stuff and some video work. Will be
doing more video in the future trying to create some Blu-ray
presentations of our high end work. Maybe a game or 2, FSX? But not
a big gamer.

Plesae help me figure out what type of video subsystem to use.

Thanks,

Roveer