Radeon question....

How does a Radeon 3850 w/ 512GB RAM versus or compare to a Radeon 5450 with 2GB Ram?

512MB and 1GB respectively... sorry... LOL.

and a system ram of 4GB and a dual core pentium 3.4 Ghz (3.4 X 2)

3850 is superior by ALOT.. seriously its closest equal would be the hd 5570 if i had to pick the 3850 would be the clear winner but tbh i recommend choosing neither if i could for a much softer on the system hd 4670 or 5670 as the 5570 has a heat problem and the hd 3850 gobbles up power.