That's an awesome card to get for free and has pretty low power requirements so should run on a modest power supply. For today's standards i'd say it's lower midrange so it handles games pretty well. Can you tell us the rest of your specs?
These are the rest of the specs for this actual card, copy and pasted from where he bought it.
Item Description:
•Product Name: VTX3D 1GB RADEON HD 5770 PCI-E 2.1
•Web Address:
www.vtx3d.com
•Model Number: VX5770 1GBD5-HV2
•Package Type: Retail
•Warranty: 2 Years
•Chipset: ATI Radeon HD 5770
•Interface: PCI Express 2.1
•Video Memory: 1GB
•Memory Type: GDDR5
•Engine Clock: 850MHz
•Memory Clock: 4800MHz (1200MHz GDDR5)
•Memory Interface: 128-bit
•Stream Processing Units: 800
•RAMDACs: 400MHz
•Max. Resolution: 2560x1600
•Connectors: VGA‚HDMI‚DVI-I
•DirectX Support: 11.0
•OpenGL Support: 3.2
•Compatible OS: Windows XP‚Windows Vista‚Windows 7
•Gross Weight: 0.76Kg
•Special Features: ◦ATI PowerPlay technology
◦ATI Avivo HD
◦ATI CrossFireX
◦Unified Video Decoder 2 (UVD 2)
◦Accelerated Video Transcoding (AVT)
•Package Contents: Video Card‚Quick Installation Guide‚Driver CD
•Keywords: Video Card‚Graphics Card‚1GB‚ATI Radeon HD 5770‚CrossFireX‚GDDR5‚HDMI‚ATI Avivo HD‚ATI PowerPlay
If you need the specs of anything else please ask and i will put them up.