crossfire or sli setup on my new build, worth it?

A single 8800GTX or R600 will most likely do the job. Heck, a single 8800GTS can do the job.

Best way to see, is to get one card, and it it doesn't do the job, then you can add another. I wouldn't get two cards at once right away without knowing if it will provide any benefits.

This is what I was thinking but it does invole buying a much more expensive motherboard and power supply.

Since one will do what i need since i will only have a 22" monitor i think I will stick to a non dual card set up so i can save some money and put it towards other parts

I'll go along with Prozac and Stranger with one caveat. When the DX10 games finally come out, a need may appear for SLI or Crossfire to play them with all the settings maxed out. That need isn't here yet, so for the moment, I'd get one card.

Another thing is that by the time a need may become apparent, new cards may be out that speed things up enough so that SLI/Crossfire again becomes unnecessary. Can't say for sure, as that gets into predicting an uncertain future.