Your system beats my current one (new one arriving next week hopefully) and while I lag shockingly in Org etc (down to 5-10 FPS), it's never so bad that /follow breaks.

Mine is set up like this:

Main - c:\wow - full graphics settings
Followers - c:\wow2 - all graphics turned down and sound disabled.

I used to run each follower from a different install of wow (a la, wow1, wow2, wow3, wow4, wow5) but found the performance to be better by reducing the number of installs from 5 to 2.

The other big consideration - you XP'ing or Vista'ing. 32 bit or 64 bit?