I'm running 5. I have the main toon run off core 1, alts 1&2 run off core 2 and alts 3&4 run off core 3. I leave core 0 unhindered for browsing and whatnot. All of my clients are being run out of one WoW directory at the moment and I'm not having any problems with that. I have the 4 alts on the left screen and the main on the right. Since my screen res is an odd size (1440x900) I asked Keyclone to make a new maximizer layout for me and he did! Please note that my settup is the opposite of his since my right screen is 'screen 1' according to windows.

Here's his example screen shot:



#
# generated by keyclone on 21 SEP 2008 11:20:20 EDT
#
D,1440,900
R,'region1','\\.\DISPLAY1',0,0,1440,900,(119.0),(1 440x900),0
R,'region2','\\.\DISPLAY2',0,0,720,450,(120.0),(14 40x900),0
R,'region3','\\.\DISPLAY2',0,450,720,900,(121.0),( 1440x900),0
R,'region4','\\.\DISPLAY2',720,0,1440,450,(122.0), (1440x900),0
R,'region5','\\.\DISPLAY2',720,450,1440,900,(123.0 ),(1440x900),0