Unfortunately, I don't own those games. Firingsquad does have Fallout 3 numbers-
Doesn't seem to be a very demanding title overall as a single GXT 280 will push it well up to 2560x with 8xAA.
I remember the days when it cost 500-600usd a video card to do Tri-SLi, aka up to 1800usd for cards alone. No, I didn't bother with it then.
I already had a GTX 260 192SP since their release, and ordering two Evga GTX 260s off of Newegg to go Tri cost me 440usd total. I planned on going X58 and I7 920 regardless. It just so happened I really liked the Evga X58 mobo so I went with it and eventually Tri-SLi.
Another thing that pushed me that way was when I ordered my first vanilla Evga GTX 260 I received one with a core 216 GPU. I promptly ordered another for Tri-SLi @ 220usd when I noticed this.
If you play 1920x and like to run the highest level of AA and detail possible Tri-SLi is solid. It also does very well on the X58 platform due to its insane bandwidth. It's also good for people sensitive to FPS dips below 30.
I play a lot of AoC @ 1920x with SM3, bloom, full shadows, 16x CSAA|16xAF, full quality ground radius, and the rest set to high. I hit 46FPS worst case scenario.
As far as PSUs go if you have limited space in your case and want a solid PSU try the below one-
If space isn't a concern-
Those should last you a while.
BTW I haven't felt or seen what some call microstutter with GTX 260 Tri-SLi and an overclocked I7 920 on the X58 platform using triple channel DDR3.
If a person plays below 1920x, doesn't use 4xAA or better, and mostly plays titles where SLi doesn't work or scale well, they should probably skip both SLi and Tri-SLi. Also if mins below 30 don't bother you should probably just go SLi instead.