6450 or 520

I need a cheap low power graphics card. I have narrowed my choices down to these to cards.

Gainward GeForce® GT520 1024MB
GPU :NVIDIA GeForce® GT520
GPU Clockspeed :810 MHz
Memory :1024 MB DDR3 (64 bits)
Memory Clockspeed :535 MHz
Bandwidth :8.56 GB/s
Ramdac :400 MHz
Bus  CI-Express 2.0
Cooling :Fan

and



Radeon HD 6450
Bus Interface: PCI-E x16 (PCI-E 2.1)
Memory: 512MB / 64-bit DDR3
Clock Speed: 625MHz Eclk / Effective 1334MHz Mclk
Cooling System: Single slot, Passive Heatsink
Bracket: Full Height
Display Support: DL-DVI-D, HDMI, VGA
HDCP: Yes
Eyefinity Support: No
Hyper Memory: No
Microsoft DirectX 11 Support
200-240 GFLOPS Single Precision compute power
TeraScale 2 Unified Processing Architecture
AMD Eyefinity multi-display technology


I know they are both pretty weak cards but which one would be the better of the two? How much more powerful is one from the other?

Thanks