While the NVIDIA GeForce GT 520 may be a "Fermi" graphics card, its performance is not very stellar. The OpenGL performance of this low-end graphics card under Linux was easily outdone by the Radeon HD 4650, which is two generations old on the AMD side and now just costs around $40+ compared to the GT 520 at $60 or more. Beyond the obvious OpenGL advantage, the Radeon HD 4650 is well-supported now by AMD's open-source Linux driver stack with KMS and Gallium3D support, where as all open-source NVIDIA support is provided just by the open-source community when reverse-engineering the NVIDIA blob. About the only major advantage the GT 520 would still carry is its support for VDPAU using the PureVideo HD engine when using the proprietary driver. AMD's X-Video Bitstream Acceleration (XvBA) API and implementation still is not as good as VDPAU found with NVIDIA's driver and their hardware, if you are interested in a media/HTPC-type system.
Except for Unigine Heaven, the GeForce GT 520 was at least a modest upgrade over the GeForce GT 220. The GeForce GT 240 was a much stronger graphics card, should you be interested in an entry-level NVIDIA graphics card.
What is unfortunate about the EVGA GeForce GT 520 (01G-P3-1526-KR) specifically is that it was the warmest of the seven graphics cards that were monitored, and was even measurably warmer than a passively cooled Radeon HD 5450. Its power consumption was at least in line with the other graphics cards of its class.