I got a hp s5503w slimline desktop and i wanted to get a better video card what

How much were you willing to spend ? Without that information we cant help you very much.

220W PSU. You're not going to be able to do much.

You have many options to upgrade,but first need to change the PSU,with 200 standar power supply all low profile card except thecheapst,doesnt works fine, buy this power supply http://www.newegg.com/Product/Product.aspx?Item=N82E168... and you can run the highest low profile card like this http://www.ebay.com/itm/Afox-AMD-7850-2GB-DDR5-PC-Gamin...
or if you need so much power,you can got the 7750 Low profile card for 100 bucks and a 300 watts PSU for 60 bucks and still running the last games in high settings

With a slim line case you are limited to what you can get for a video card and power supply. Like the one listed here.


http://www.newegg.com/Product/Product.aspx?Item=N82E168...

You are also limited to a low profile video card like the one listed here.

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

http://www.newegg.com/Product/Product.aspx?Item=N82E168...