I've been out computer hardware since the beginning of last year, so I could use some help. I've got a BFG 6800 GT PCI-Express card, with a 500 Watt Aspire power supply. Would it be best for performance and price to buy another identical card and run SLI, or ditch this card and buy a new one altogther. I'm concerned that running SLI might strain my power supply unit. Suggestions? BTW, I've also got a AMD 3500 Winchester, 80 Gig SATA harddrive if that makes things more clear.