Sweet! I just dropped a BTC address in my signature, fire at will
Regarding dummy connectors, they're not needed on Linux since X initializes all of the adapters automagically, regardless of whether it thinks there is a monitor connected, or not. When you add the additional video cards, you'll just need to reinitialize your xwindows config like this:
aticonfig --adapter=all --initial --force
I still highly recommend pooled mining though.. you'll be able to realize instantaneous benefits (in received bitcoins from the pool) in proportion to the amount of computing power you contribute to the pool, ratioed to the total. For example, on deepbit at today's difficulty, you'd get like 8 BTC/day with 4 Ghash/sec. Essentially it's exactly the same thing as you'd get mining solo, without the wild time variance between blocks found. Hopefully that makes sense.