MSI gtx 560ti SLI or MSI gtx 650 SLI?

Hm?
You can't SLI the 650.

But you can Crossfire a 7770  

Just a heads up OP.

*Edit, why would he be trying to SLI two $100-$200 cards? Why not get a $200-$400 single card?

AMD drivers, ew.

But even then, SLI isn't all that better neither. If OP hasn't bought the card(s) yet then I don't know why he is contemplating it.

A single 7870/7950 or 660ti would be easier and have less wattage...

How good is a 660? Does a 660ti give me a drastic increase over the 660

http://www.anandtech.com/bench/Product/660?vs=647#

Not really. You can get a 7950 for $300 as well and it trades blows with the 660ti, also AMD cards are better at overclocking than Nvidia.

http://www.anandtech.com/bench/Product/550?vs=647

just to chime in the GTX 650 is a horrible gpu for the cost as a HD 7750 outperforms it for half the cost ?

http://www.tomshardware.com/reviews/geforce-gtx-660-gef...

What is your budget? It sounds like you are wanting some good performance, can you jump up to a 670?

Trying to keep it under 300

under $300 then a HD 7950 is the way to go

Sapphire HD 7950 $279 AR
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

I really dont want to leave Nvidia. You've got to convince me. Whats better about this ATI card.

Here's the reality. If you don't want to leave Nvidia then go for a GTX 660ti or a 660. We've given you the benchmarks, gave you answers and have talked about the better side of GPUs this generation.

If you don't want a AMD GPU, then by all means, go the Nvidia route and be happy.