As Scud had already stated, upgrading your power supply and installing a video card are pretty easy to do, if you do your homework right and get the right hardware.
About 4-5 years ago, I got away from my integrated graphics card and purchased a NVIDA GEforce graphics card that came with a lifetime warranty. In order to use the graphics card, I also purchased a new power supply that had the proper amount of watts to handle the new graphics card.
I purchased both from Newegg.com and based my chooses on the ratings and feedback from other customers.
http://www.newegg.com/
Believe it or not, my graphics card actually went bad on me after having it for about 1.5 years and the manufacture replaced it for free with a even better model than I had. Other than that, I haven't had any other problems with either the power supply or the video card.