Upgrading - Budget Range is $300 - $400. Upgrading my older PC.

Approximate Purchase Date of parts: Within the next 2 weeks.
Budget Range: $300-$400 After Rebates.

System Usage from Most to Least Important: Gaming, surfing the internet, Photoshop, watching movies, Home.

Parts Not Required: keyboard, mouse, monitor, speakers, OS, Power Supply 550W.

Preferred Website(s) for Parts: newegg.com, amazon.com, tigerdirect.com

Country: USA

Parts Preferences: I would like to use an Intel CPU & Nvidia Graphics Card

Overclocking: Maybe

SLI or Crossfire: Maybe

Monitor Resolution: 1920x1080


Hello, I'm new to the community, but I came here first to seek help from the brilliant minds of Tom's Hardware with my upgrading dilemma. End results for PC: I want to run World of Warcraft flawlessly. Also, want Guild Wars 2 to perform above 60-80 fps [hopefully in WvW too  ] I solely want to upgrade the CPU and Graphics Card, but willing to consider other upgrades if needed. My computer specs are as follows:

OS: Windows XP Home Edition
MoBo: Asus M3A78 Pro (AM2+/AM2 AMD 780G HDMI ATX AMD) 140W CPU Support
Graphics Card: MSI N9600 GT-T2D512-OC
Ram: OCZ Platinum Series 4GB (2 x 2GB) 240-pin DDR2 SDRAM DDR2 1066
CPU: AMD Athlon 64 X2 7750 Kuma 2.7GHz Socket AM2+ 95W Dual-Core Black Edition
Hard Drive: Western Digital Caviar SE 320GB 7200 RPM Sata 3.0Gb/s
Power Supply: 550w
Computer Case: Raidmax Smilodon Extreme Black ATX-612WEBP

Thank you in advance. If any other information is needed, please don't hesitate to ask.