Do I sell both of my older gpu's to buy a one newer gpu?

Over the past few weeks I acquired a 5850 for free with a broken fan. I replaced the fan and applied new thermal paste. The card is running great now. I also recently traded my GTX 650 for a 5830. My idea right now is to crossfire them in my new build. I know one of these cards alone would bottleneck the build, but since there's two of them, they would perform pretty well..right? 

To me, it makes more sense to keep both of them and crossfire them instead of selling them to get something new. I probably wouldn't get more than 115 max per card, and that's MAX. It's hard to find a decent graphics card for under 200 dollars anyway, and I'm on a VERY limited budget, as I already have to buy a new mobo, processor, and memory.

Should I keep these cards and crossfire them? I know they're old, but they still would perform well, right? I don't play too many graphically intense games, but I'm considering playing some. Would these cards be good for at least one year?

I have a friend that would be interested in buying both gpu's for 250 dollars. That gives me enough room to work with for a decent card. I was considering either one of these-

Those are my nVidia options, anyway. I don't have much experience with AMD gpus, so if you guys could make a suggestion that would be great.

Well according to AnandTech one is more powerfull then the GTX 650 you traded.

You could always get a 7870 like this one

Also they are neck and neck with each other.

you could also go for a 7870 Tahiti LE (or XT) which for the same price as the 660 TI will give you around 35% better performance in game with AMD's new drivers

That's where it gets interesting, though. If you look at the benchmarks for 5850s ran in crossfire, they have higher framerates than the 7870 or 660ti in the few games that are included in both benchmarks.

By the way heres a link

Looks pretty tempting, actually. How would that compare to crossfired 5830s?

they are only faster in older games like crysis, also a 660Ti use about a 1/3 of the power as a 5850 and a 5830, almost a 1/4 actually, the 5xxx series tesselator is weak thats why it can't handle newer games

my personal recommendation is the 660Ti

The 7870 can be OC higher then a 660ti, also the drivers AMD is pushing out have been great

Sell them thats a good deal for you and you get to buy new stuff 

Well, given that my it was my old Radeon 5830 I traded for the 650-Ti, and apparently my old GTX 570 seems to be working now without issue, I appear to be in same boat with Toast. Do I use one for a dedicated PhysX unit, or sell both to get a new card. XD

Sell both, PhysX is in such a small amount of games its not worth it.

Haha jerm how funny xD At this point I think I'll be going for the 7870. Looks tempting.