Quote Originally Posted by Warsaw View Post
You might be able to get away with putting a Galaxy GeForce 9600GT in your current HP. It's low profile, works with low wattage PSUs, and is respectably powerful.

http://www.newegg.com/Product/Produc...82E16814162016

There are also mATX PSUs that could fit your Slimline should you desire. This is probably the cheapest way to upgrade performance if you want a stopgap until you build a new PC.
Would any 9600 GT work with a low PSU? I don't use a slimline case so I don't think need to worry about size as much.