If you need to buy a multi monitor card I recommend Maxtor. I run 4 monitors on one machine with 2 Maxor dual monitor cards. I bought mine used on ebay for about $40 each instead of $500 for a quad monitor card.

As far as machines, it depends on what you are using it for. If just surfing the net and email I would use consider a bottom of the line E Machines. Normally under $300 at Best Buy and of the 5 E Machines computers I have had only one has ever had a problem. I don't have time for online games so the high speed stuff just doesn't interest me.