Yes, get rid of your old Sct A board, replace it with ideally, a Sct 939 AMD 64 cpu - the more expensive, the faster! - then go for2x512MB RAM sticks.
You will get great performance from a 6600GT with such a CPU & Mobo etc.
The older SCT A CPU will simply be a bottleneck for the new card.
I'm an "Intel Man" you may say, somebody more familiar with AMD kit will no doubt put you straight. -
Congo or Dan spring to mind.....
