Best NVIDIA GPU under 60$

[dragonfrom12]

looking for a GPU upgrade on this desktop tower. the GPU Right now is AMD X something series and it sucks. im personaly an NVIDIA fan. the slot i dont know if its a PCI X 2.0 or 1.0 or 3.0 but i dont care.

 

[dragonfrom12]

found Mobo for $65 with rebait on tigerdirect.com. then for RAM. im going to find 1 4gb of vengence or something is what i want to do.

UPDATE: found some RAM. how about this???
http://www.newegg.com/Product/Product.aspx?Item=N82E16820231743
UPDATE 2: im half tempted to go lower on the GPU because i dont need a 640. i think a 620 would suite me till i upgrade again. any ideas?