Hi, the installed psu is 420w, the card pulls about 65-75w and the requirements for WOW (world of warcraft) are:
OS:
Windows XP 32/64-Bit (Service pack 3)
Windows Vista 32/64-Bit (with the latest Service Packs)
Windows 7** 32/64-Bit (with the latest updates)
Processor:
Minimum: Intel Pentium 4 1.3 GHz or AMD Athlon XP 1500+
Recommended: Dual-core processor, such as the Intel Pentium D or AMD Athlon 64 X2
Memory:
Minimum: 512 MB RAM (1GB for Vista users)
Recommended: 1 GB RAM (2 GB for Vista users)
Video:
Minimum: 3D graphics processor with Hardware Transform and Lighting with 32 MB VRAM Such as an ATI Radeon 7200 or NVIDIA GeForce 2 class card or better
Recommended: 3D graphics processor with Vertex and Pixel Shader capability with 128 MB VRAM Such as an ATI Radeon X1600 or NVIDIA GeForce 7600 GT class card or better
Storage: 15 Gigabytes or more free hard drive space is required
Sound: DirectX-compatible sound card or motherboard sound capability
Thanks