Need help picking out my graphic Card (PCIe)

 
Manufacturer: Dell
Model: Dell Optiplex GX620 Desktop (Not Minitower)
OS: Windows 7
System type: 32 bit OS (Should I upgrade it to 64 bit after I upgrade my Ram to 3 GB?)
Ram: 1 GB (I'm upgrading to 3 GB tommorow)
PSU: 305w
Processor: Intel(R) Pentium(R) D CPU 2.80 GHz 2.79GHz (I think it's a Dual)

I was looking at the MSI ATI Radeon HD6450 1 GB DDR3 VGA/DVI/HDMI Low Profile PCI-Express Video Card R6450-MD1GD3/LP, do you think this will be compatible on my computer?

Product Features:
Chipset: Radeon HD6450 Engine Clock: 625 MHz Video Memory: 1GB DDR3
Memory Clock: 1333 MHz Memory Interface: 64-bit Bus: PCI-Express 2.1 x16
RAMDAC: 400 MHz Max. (Since thats the Max. can I still Run it?) Resolution: 2560 x 1600 Connectors: DVI; VGA; HDMI
Thermal: Fansink Support Microsoft Windows 7 Support ATI CrossFireX Technology
Support AMD Stream Technology Support Blu-ray and HD DVD
Support HDCP - High-bandwidth Digital Content Protection
Support Microsoft DirectX 11 and OpenGL 4.1 Low Profile Design


http://www.amazon.com/gp/product/B004X6ABTM/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=A2L77EE7U53NWQ

Can you also please recommend me graphic cards $75 and lower, on a tight budget.

Tell me if I need to add enymore details to help you guys out.
Thank you for all your answers!!