2 HD 4830 in crossfire or 1 HD 4850??

Well as for the CPU, the X3 720 is cheaper than the E8400 and for gaming both are very good but the X3 will outperform the E8400 in multi threaded apps...
So x3 is a better choice...
As for the graphics card, take a look at the 4770...It will perform nearly similar to the 4850s at low resolutions and is about $100...So first check how it performs and if you are not satisfied with the results, get another 1 in crossfire...

But I would suggest a single powerful card to a crossfire setup as they dont scale well in all the games...So get the 4850/4770...

is der any 9800 series cards in da price range of 4830??also is ati n nvidia similar in performance..here sme says nvidia is gud while others support ati..

Why not just get 2 4830s and crossfire them? They're only just barely slower than the 4770s, and it would save you $40 (for a pair). Switching to the smaller 40nm process is mostly good for the manufacturer, because they spend less per chip. As for the GDDR 5 RAM, again, it costs the manufacturer less to make. It does run faster, but then they counter-acted that move with the 128 bus instead of the 4830s 256 bus. As consumers, your boards run cooler (big deal), and it takes a little less power to run. I realize that power costs money, but you would have to run your PC nonstop for 1 to 3 years (depending on where you live, energy varies from 6.7c to 30c / kWh). Seriously, just get the older 4830s until the 4770s come down in price. Most places are currently discounting those 4830s to get them off of the shelves.

OK then, if you're set on getting one board, just opt for the 4830... If you want more power, you can always overclock it. Getting the lowest board in a particular series usually renders the best OC. Often times, it gives you the same max as the highest priced board would anyway. It still boils down to, the new 4770s don't really offer much more than the older 4830s, but they cost more. Besides, if you can pick up a used 4830, you could save even more.