Major Audio problems

Please help!

System: Dimension XPS T500MHz Pent 3

Operating system: Windows 98SE

Sound card: Turtle Beach Montego II A3D 320v Sound Card

 

I recently re-formatted my harddrive (with Dell's help) and now I can only play CD's.  Songs I've downloaded give me two errors.

 

I use Real Player version 10 and the error message is :Cannot open the Audio device, another application may be using it.

 

I tried to use Windows Media Player version 9 and the error message is:C00D11BA, cannot play the file. 

 

I've tried re-installing the sound card and I still have the same problem.

 

Any help would be appreciated...thanks.