I don't think that HD4850 is slightly better that 9800GTX+
I know some people could post some reviews that shows HD4850 being better than 9800GTX+
But I have also seen reviews that show 9800GTX+ being better than HD4850 overall
EDIT: You can get GTX 260 for $169.99 after MIR
Newegg.com - EVGA 896-P3-1260-AR GeForce GTX 260 896MB 448-bit GDDR3 PCI Express 2.0 x16 HDCP Ready SLI Supported Video Card - Desktop Graphics / Video Cards
Enter the promo code VGA111810
Then get the rebate from here
http://images10.newegg.com/UploadFil..._-NA-_-NA-_-NA
It comes with free far cry 2 game as well