Problems Gaming

My system is not recognizing all resources (I have 3Gb RAM on my new gtx580, system reports 1GB), my comp is loaded to game but I cannot play as the system freaks out and hard drive goes over 100% write, crashes games. I avg 10fps until I get in an instance or around other players, then drops to 1-2 fps. Game crashes, memory and hard drive goes 100% usage/write, takes me 10 minutes (no exaggeration) to transition game instance/load screens. Everyone blamed Vista, so I bought Win7. Turning off Norton has no positive effect. I know folks with off the shelf laptops that run SWTOR at 60fps and better. I have spent 1000USD upgrading this PC, it still doesn't work worth a crap, I am not sure where to turn and am about ready to go MAC. Figure I would give this forum a shot first. Any advice? Thanks.

So you'd rather go to a Mac that costs twice as much and barely has any games to run? Oh, and lags 6 months behind in technology?

Now, on a serious note, you commited a cardinal mistake of trying to shoehorn high end upgrades into an OEM system. If you want to upgrade, do it right. Most likely, those components are pulling too much power for the puny HP PSU or are generating FAR too much heat for what that OEM case was designed to handle. If you had planned to spend that much money on upgrades, they should have included a new case, mobo, and PSU. Everything else can be moved over.

That all being said, let's start at the beginning. What is the stated/rated wattage of your current PSU?

Many thanks guys, you both hit the nail on the head. I had a pro come look at it, I put good gear on old good gear, and MAC would be a bad choice for me given my applications and gaming preference.

I have a template now to build the rest of a great Windows system (new built comp since I already bought good key pieces), and I can put the old pieces back in this one and continue to use it as well for lower end application as a type of server/storage.

Thanks for your merciful and accurate responses to my inept plea!