If you have a Regualer Size Inspiron 531 tower then yes this card will get installed without any hassels and your computer power supply will be able to support that card.

There is also a Inspiron 531 slim tower model if you have one of those then this card wont fit the expansion slots at the back.
You would need a reduced size graphic card for them.

If you want a slimer one of that card its also available by Asus on newegg at a little less price. Only diff. is the HIS One is overclocked by 30mhz. Would barely make a diffrence. Check it:
http://www.newegg.com/Product/Product.aspx?Item=N82E16814121274

Hope it helps.
Rocky : )