I like the second one. The thrid link takes you to the second build also, but still like the second build.
edit: nvm....i didn't catch the 2x2gb..still like the second one though
You could keep the fsp 450w psu from the 1st build. Your not getting much more power on the +12v. Unless you want the modular psu for a cleaner look which is cool and justifies the extra money i guess.
I guess you want to sli latter with the 650i mobo. Sli isn't that great though and the 650i is only x8 x8 speeds which further inhibits the performance boost. I would either get a 680i board if you really want sli that bad or get a good 965p mobo (the asus p5b-deluxe is an awesome board).
I would say go with xp instead of vista since there seems to be bugs still left to work out with the new operating system, but i think you might as well get vista since your building a systm from scratach. Just know that you might run into some problems with vista since its still a fairly new OS.
Make sure to get a tube of artic silver 5 w/ that zalman 9500...better temps.
Every thing else looks good to me. If you follow my suggestions, we'll have similar builds (its a common combination right now so not much of a suprise
) except i have a stacker and xp pro.