comparable or compatible?
Comparable, no. The P5B DELUXE is a motherboard and the EAH5450 Silent is a graphics card.
Compatible? Yes. Because the P5B DELUXE has a PCI-E x16 slot for the EAH5450 Silent graphics card to go in.
But to be honest, I would advise not getting that card as an upgrade. It is a really slow card by today standard. Try to get a 6570:http://www.newegg.com/Product/Product.aspx?Item=N82E16814102942