HD 7770 worth it?

Hello,

I just ordered a budget system as follows:

AMD Phenom II X4 965 Black Edition Deneb 3.4GHz Socket AM3 125W Quad-Core Processor

ASRock 970 EXTREME3 AM3+ AMD 970 SATA 6Gb/s USB 3.0 ATX AMD Motherboard

G.SKILL Value Series 8GB (2 x 4GB) 240-Pin DDR3 SDRAM DDR3 1333

ASUS HD7770-DC-1GD5-V2 Radeon HD 7770 GHz Edition 1GB 128-bit GDDR5

CORSAIR Builder Series CX500 V2 500W ATX12V v2.3 80 PLUS Certified Active PFC Power Supply

plus a few odds and ends to complete the build. I have an existing case,hdd and monitor.

Its been 14 years since i assembled a computer, luckily not much has changed as far as building one.

My problem , besides accidentally clicking the wrong 7770 card, is my wife has generously agreed to pad my build budget another $118.

Now Im stuck with deciding if I should get another 7770 (@ $118) or returning the one I ordered and try to find a single card at $236 or lower that will out perform the 7770ghz's crossfired.

My original budget was $400, I came in just under this including shipping.

From what Ive been able to find there is no $236 card that will out perform 7770's in cf. Is this correct?

Remember (please) I'm 42, been out of the game for 14 years and have absolutely no more cash than what the $118 and returned $118 for $236 can yield.

Thanks in advance! My two teenage boys and two baby girls thank you also!

PS. Sure wish the great people at Tom's would include sli and cf figs in their gpu hierarchy charts. That would be a boon for budget (poor) guys like me!

Also please keep in mind my PSU limit is 500w. This was a big factor in deciding on the 7xxx GCN chip. I know AMD recommends 600w but, the second VC wasn't an option at the time of order. With no dvd or anything else besides mother board, cpu and vc's I'm hoping it'll be ok. Chose to ditch dvd/br drive, not much use these days, even less in days to come.

To show my age a bit my first video game system was a Telstar 1000 and my first computer was a 8088. We've come a long way!