I have a 240GB Samsung 840 Pro and I'm getting ready to build a new system this weekend. Before I pillage my old system for its PSU, I'm wondering if I should stick the 840 in there and format it, or update its firmware(?) or anything before I put it in the new system and install Windows 7... or if I should just put it in the new machine untouched and let the install do the format?
You don't have to do any formatting on it as Windows setup will let you do it when you go to install Windows 7.
When you're ready to actually do the install of Windows,
Go into the bios and change the IDE mode to AHCI instead of IDE. This enables advanced communication features for SSD drives and also SATA drives, but mainly SSD(s). You can't change it after the install unless you do a reg fix.
Then run the Windows setup DVD.