Dual Video Card Questions

[MassMoron]

Ok, I'm not exactly sure how dual video cards work so if I could get a simple explanation that'd be really great!

Also, I'm looking at getting an Alienware desktop and theres the option of 1 GeForce 8800 GT or 2 of them. My question regarding this is, is it really necessary to have two or one would say that the 8800 should last me a while for upcoming games.

Thanks!

 

[Ambushed]

Your two graphic cards need to be exactly the same as each other and you also need to check if your motherboard is supports SLI technology - http://en.wikipedia.org/wiki/Scalable_Link_Interface.

Read that, it should tell you everything you need to know how to dual video.