What is liking causing the "HUGE" lags spikes is your cpu. A amd 2600 is old, especially if your playing newer games. A decent card,which is what you have, won't help if your cpu is to weak which I believe is your case.
I'd either get a new system or start saving for one. You'll need about $1000-$1500 for a decent/good gaming rig. You could save some money by keeping some older hardware but personally I would replace everything. Kingston ram is ok but there is much better out there. Hard drive need to be bigger and probably faster. You don't need a Raptor drive but Seagate and Western Digital make very good,fast and big(500gb or more) drives for around $100-$150. Some can go for only $80. Depending on which Audigy you have, it might be worth keeping or just stick with onboard sound, which has got alot better lately.