AMD Athlon 64X2 System Overheating Question

I am not a Computer wizard. I bought all my computer parts separately off of Newegg and Tigerdirect and put this system together. I paid a Computer guy to hook the motherboard to the case and load the operating system and get it running. The computer was built to mostly tp play WoW and LOTRO lag free at max settings which it can't do. I also do a lot of internet surfing. I downloaded Everest and noticed my GPU temperature runs normal at the desktop around 57 C. In LOTRO at medium settings I run upwards to 79 C. From what I see on the internet my CPU should never go over 63 C. I have two video cards SLI together but only use one for now because it seems like I have more lag with both running. I would like to upgrade this system a bit to run LOTRO at max setting lag free, safely. This is what I have.

Microsoft Windows XP

XION Onyx XON-303 Black/Blue Steel ATX Mid Tower Computer Case

CPU: AMD Athlon 64X2 Dual Core Processor 6000+, 2999 MHZ

Motherboard: K9N SLI Platinum NVIDIA nForce 570 SLI Chipset Based

2 Video Cards: PNY NVIDIA Geforce 7600 GS 512 MB

Ram DDR2 2 GB

Monitor: Acer AL2216W

Power Supply: 750 Watt EPS12V Silencer from PC Power & Cooling.

PREFERRED WEBSITE(S) FOR PARTS: Newegg & TigerDirect COUNTRY OF ORIGIN: USA

OVERCLOCKING: No, can't keep system cool now as it is. Maybe SLI: Yes would like to I figure 2 Video Cards better then one.

Fans: I have a 120 Fan on side of computer directing air on CPU fan. A 120 Fan at back exiting air. A smaller 80M fan directly over both video cards on side of case and a 120 fan in front puling air into case. The CPU fan is the one that came with the CPU.

Any advice you can give me to make this system better for what I need I would really appreciate it. Mainly running LOTRO Max settings and at safe temperatures. Also I am looking at throwing together another computer that can run LOTRO max settings for my wife. Any suggestions for a build for that computer would be nice and I am trying to keep the price down to around $1400.00. Either AMD or Intel processor is fine with me. SLI or crossfire is fine as well. I will most likely upgrade this system and get the other one together in the next month and a half. Thanks so much in advance for any help ya'll can give.