[JSLTIGER]

Feasible? Probably. Would you really want to? Probably not.

In order to hook something like that up, you'd have to leave the side of the case open so that you could run the power cords to the proper components. Depending on the design of the case you have (I'm not entirely sure how HP designs theirs), opening the side of the case may actually hurt the airflow inside by preventing an airflow stream from forming. Also, you'd be exposing a lot of components to a lot more dust and the risk of something interfering with the fans inside the case. Much higher chance of component failure that way.

Would what you are suggesting work? Yeah, probably. Do I think it's a good idea/would I do it? Absolutely not.

If you're thinking about going this route, I'd suggest just buying an entirely new case, demounting the motherboard from the slimline case and remounting it into the new case (provided you know what you're doing of course. Otherwise you're just begging for trouble and may fry the system). You may be able to take the optical drive and move it over as well. Not only would it solve your problems with the slimline case, but you'd be able to purchase a full-size card (greatly expanding your options) and a normal PSU. That being said, I don't know that what I'm suggesting is feasible given your budgetary situation.

EDIT: Don't forget to check the reviews of this thing...not the best in the world...