Howdy Ganjakru and welcome to the forums!

keyclone should work fine with freecap, if you enable auto-add-windows-titled.

doing it this way, you can create a command to start your freecap-wows... and your wows will pop up.
but.. they won't maximize properly. to do this, right click each wow in the keyclone main list.. and select 'maximize...' .. then select the region you wish for it to be moved to.

as for your machine, i am 5-boxing on an amd 3800+ single core.. w/ 3gig and 8800GT OC @ 5/20 and 1280x1024x2 horizontal span... so i would guess your machine will work fine. just remember to set the maxfpsbk and maxfps

if you have any problems, please feel free to drop me a note.

have a great day and welcome to multiboxing