Absolutely. I think most of us are excited to see what the 7950 and 7970 bring, even those who plan to wait for 6xx from NVidia (these AMD cards should provide a little insight into what performance can be expected from cards using 28nm). Depending on how the pricing shakes out, I'll probably invest in a crossfire setup of one card or the other in Jan.
So- to come back to your predicament, a second inexpensive 5850 would be ok. Just don't invest too much in the 5xxx series at this point. Cheers!
thx for help bro, really appreciated