That is an excellent price on a good card that 2 years ago was considered the card to have for gaming. Now it is getting a little long in the tooth. I generally recommend getting a newer card that has the latest technology and generally runs cooler, but you often get the most performance for the dollar with the older technology.
I don't think I would buy two for Crossfire tho - although it still might give you the best performance for the dollar - but if you are going to spend $120 I thnk I would go for a newer card even if it might be a little slower. Get a single new card now and perhaps CF it later for even more performance.
If you want to spend that much, I recommend the GTX 460 768MB card. It is a solid card that can be found at a discount right now because it is being replaced by the GTX 550 Ti, but the new card is slower. The 768MB version of the GTX 460 is only slightly slower than the 1GB version, but costs substantially less. See the slight performance difference in this article:
http://www.tomshardware.com/reviews/geforce-gtx-460-gf104-fermi,2684.html
Note that on the THG Best Card for the Money article linked below, the GTX 460 1 GB is one of the cards recommended at the $200 price level. This card is almost as fast and as shown in the review above, and costs quite a bit less..
http://www.tomshardware.com/reviews/best-gaming-graphics-card-geforce-gtx-590-radeon-hd-6990,2879.html
For a specific card, I recommend the MSI Twin Frozr because of its effective but quiet heatsink/fan, factory overclock, and good price – only $130 after rebate.
http://www.newegg.com/Product/Product.aspx?Item=N82E16814127519&cm_re=gtx_460_768mb-_-14-127-519-_-Product
You can find more information about reviews on all of the cards you might be looking at at:
http://www.upgradevideocards.com/reviews.html
Have you included in your build a PSU that is large enough to run the cards your are looking at?