What PCI video card for widescreen + Divx movies?

I am looking for a PCI video card to watch Divx movies (compressed 700MB/1.4GB format) and some DVDs on my Dimension 2350. The integrated video does not support wide formats so I am looking for a video card that has the following:

- PCI interface

- VGA and DVI outputs

- supports widescreen resolutions

- good for Divx and DVD playback (noise reduction?)

- I don't play any video games

I keep hearing about GeForce and Radeon but I don't know much about video cards. Which one to get? Do I need 128MB or even 256MB?

Any recommendations? Thanks.