New 4850 and amd 5200+

Okay, this new card is kind of weird.
I just upgraded from a x1950gt and 4000+ to 4850 and amd 5200+.
For some games I deferentially see some performance.
When I run Counter strike source I only get like 40-60.
I switched out the new card for my old one and kept the new cpu.
I got a 130 in it.
So all together I am having a lot of issues with this 4850.
Is there a special Driver I need to use.
Bottom line Is it a defect or a certain driver?
Because It does kind of act like one
I can see some difference but not much.

X1950GT = DDR4
HD4850 = DDR3

CounterStrike is a CPU dependent game... it utilises much of CPU power and power of video memory....
So there will be some difference....

Try some other games....

I'd recommend you to use Drive Sweeper to clean all the drivers of ATi from the system before inserting HD4850..... coz.. drivers of X1950GT & HD4850 differs a lot... Download latest catalyst driver(v8.12) for HD4800 series...and install it..
That'll do the rest...