they will only fit in one way (unless the board and psu is 10 years old )
read the psu101 http://www.computerforum.com/10764-psu-101-a.html
it will give you an idea of what the connectors are and where they go
It's really easy, honestly, simply, unscrew the old one after turning it off and unplugging everything and then connect the new one up after screwing that one in. Your MOBO booklet should come with the places the connectors go, even if it doesn't it isn't hard to work out
*chuckles* Well my walk-through was more "Just freakin' do it!" But I will seriously do a quick little video if someone needs it of me removing a PSU and re-installing it. I about made a video and posted it, but all my equipment's downstairs, and I have no webcam for live footage
Well The other one ended up convincing me to do it and I did it. Omfg the amount of wires/connectors this psu has is terrible but I figured it all out and I managed the cables the best I can.
Damn the psu is so quiet!
I also finally installed a rear fan to blow out all the hot air.
All I need now is a nice cpu fan/heatsink and im set.