Issues after reinstalling XP Pro?

After reinstalling XP Pro awhile back I noticed two problems that I have put off trying to fix. The first is DVD playback, I have a DVD drive and watched DVD before the reinstall but now when using any media player I get this message or something similar

"Windows Media Player cannot play the DVD because a compatible DVD decoder is not installed on your computer."

Can I get the decoder for free that will allow me to watch DVDs through Windows Media Player or Real Player.

The second issue is when I try to play a game, Halo in this case, I get a message that says

"A problem occurred installing DirectDraw. Hardware acceleration maybe disabled, please run DXDIAG."

I ran DXDIAG and these notes were listed in the display tab

-The system is using the generic video driver. Please install video driver provided by the hardware manufacturer.

-Direct3D functionality not available. You should verify that the driver is a final version from the hardware

Anyone know of any solutions?

Issues after reinstalling XP Pro?ie

If you go to the windows update page, it should upgrade all your drivers and fix the majority if not all your issues. You have to choose the custom options, not the express section, and check off the drivers you need, they will be displayed by clicking on the left under Software/Hardware Optional section. It will not do it automatically and you probably have to run the update pages multiple times to complete everything.

Issues after reinstalling XP Pro?microsoft internet explorer

it sounds like you need the drivers for XP pro
fponts ideas are good, but in addition I would go to the Sonic site and download the Sonic Encoders and the DVRMS Toolbox.