My stepmother has a similar computer (same brand and size but older parts), it's not very upgradable at all! It has a tiny PSU both in wattage and size, it's a non-standard size as well, and at best you might find one that's 50-100 watt higher. But it will be some generic OEM PSU. Second thing is available space inside the case. It has very little extra space and with some finagling you might fit a Low Profile Video Card that will at best provide minimal performance increase due to lack extra PSU cables to plug into a card.
You might be able to mod the case and/or jury rig something with a normal PSU(and an adapter for the mobo's 20/24pin connecter and remove the side of the case and again jury rig a normal video card in there. But it will be super ghetto looking. That's the only real possibility for real upgrades. Otherwise not much room/ability for upgrades.