Need opinion on this budget gaming specs

I am going too change my desktop soon...My budget is around $ 510. Not more than that. Here's the specs that i go for.

AMD Phenom xII AM3 555+ (B/Edition)
MSI 770-C45
Kingston 2GB DDR3 1333mhz
Casing : Raidmax Tornado ( FULL BLACK )
PSU : SST-ST50F-ES Silverstone 500watts
HDD : WD3200AAKS 320G 16M
GC : Palit GTS 250 1GB Green
LG DVD 24X

What do you guys think of this?

I dont know the difference between having PhysX on board or Changing too HD 5750 which got DX11.

Which one is better? HD 5750 IN DX 11 OR GTS 250 which has PhysX.

+ Is this specs good enough? Planning too upgrade also in the future.