Reinstalled WindowsXP And Now I Have No Sound

Hello,

I Recently Re-Installed Windows XP On My Dell Optiplex Gx-280 ... and I Have No Sound Anymore .. Under Audio It says There are no Audio Devices Installed Also I Have a Brand New Samsung 23" SyncMaster 2333 Monitor And I Cant Install Any Of The Programs That Come With It Or The drivers ... It Says Its Not Supported By My System But It Worked Fine Yesterday Before I Re Installed Windows ... Does Anyone Know What Is Wrong ?

I Re Installed Windows Because I Had a Really Bad Virus And There Was Really No Other Way I Could Get Rid Of It ... Could The Virus Have Killed My Sound Card ? I Have No Idea What Kind Of Sound Card Is In it Because It Was My friends Computer Before And She Dosnt Know Anything About Computers ... Or At Least Not Enough To Tell Me Things Like That ! Can Someone Please HELP!