Graphics Card Suggestions?

I bought a computer with integrated graphics, but the performance is not
very good (in regards to gaming and Windows Aero) and I would like to get
something better. I do not really want to spend too much on a graphics card
($200 maximum) but need help deciding. I do not have a PCIe slot, so I need
to find a card that supports PCI. Are there any good ones that would support
the Windows Aero theme, and provide a fair gaming experience as well for
that price range? I've been told I could disable my current graphics card
and use a different one from a PCI slot, so would this work?

I'm sorry if this sounds like a newbie question, but I really don't know
much about graphics cards. I just want to know if they even make PCI graphic
cards that would be compatable with Windows Vista, the Aero theme, and
provide an okay gaming experience as I said above, as well as work with the
Vista Windows Movie/DVD Maker, which my current graphics card doesn't even
support, so I cannot even try them out. As a side note, is there any way
around that?

Thanks in advance,
- Aaron Lindsay