best bang for the buck?

I'm personally a radeon fan, but that's due to all the issues i had back in the day with nvidia cards.
While i know enough about computers to fix them, and have some electronics background, you all are more up on graphics cards.. so i am here for your input.
fan boys/girls can hang their hat somewhere else, all i want to know is what is the best bang for the buck. i'd also like to keep this price around $250 range. could be higher or lower.

will be building two identical systems that will have something like the following. as of yet i haven't done much research into what i want to use other than the basics
i5 (water cooled, thinking h80 or h100)
mobo i havent looked into yet but OC'ing is a must.
samsung 830 ssd
8gb ram
running windows 7, 64

i'd like these system to be able to age well, that i wouldn't need to replace the graphics card for a good while is ideal.

was looking at that same xfx 7850 card today.
my computer has the xfx hd 5770, i don't pc game a lot but might also get that card for my system.

gaming computer for both my kids, will be building two identical systems.
son is 8yr old, daughter is 6yr old. shockingly enough they play much more intense games than i do. mostly i stick to the xbox because i didn't have a pc able to game on and have a bunch of games for it.
i'll be getting more into pc gaming, but as of now i mostly only play blacklight on my own system.

this is what i currently have picked out.
http://secure.newegg.com/WishList/PublicWishDetail.aspx?WishListNumber=15018989

as for a case, i'm looking at building my own. still debating on if i should make a full desk with the parts built in or smaller desktops.
they will be built out of translucent and transparent plexiglass. that's if the budget by xmas permits.
either way i'll have washable hepa filters for air intake that can be slid out.
this way the inside doesn't get all dusty and the parts look like new all the time.

trying to save as much as i can on parts, and thats why i'm trying to stick around the 250 range on graphics.
right now they share a c2d 4300 (think thats a 1.6 or 1.8ghz) with pin mod to 2.4ghz or 2.6 (cant remember)
has 2gb of ddr2 (the most the mother board could take).
with a his iceq hd 4670

Tossed in an extra card for myself..
as for the MSI HD 7850 Twin Frozr 2GB, my only issue with that card is it's already OC'd and read that a stock cards OC's higher/more stable. was just one or two sites that stated that (not here) so not sure about the truth behind it. the xfx also have 2gb. but i'll leave you guys to hit me with what i should get. my main thing is that i don't want these computer to need any upgrades for at least 3 years or longer.

-- EDIT --
also want to get them into editing video with pinnacle studio like i do every once and a while.
i try to teach my kids things very early so that later down the road they have a good knowledge and wide background for jobs down the road, but in a slick way. like i'll get them into editing their PC gaming videos so they can upload to youtube and all that fun junk.
Edited by Jollyriffic - 7/23/12 at 11:02pm