He just wants to record audio through LineIn (could be LP record, video tape, camcorder, anything).
The OS, in this case Win2K, is ill-equipped to do this... you require a recording software. Many will record WAV and some will record directly to MP3, OGG or AC3 2.0 etc.
However, the selection of LineIn as source can be tricky! I have found that the full audio driver package is often required (not just the drivers) in order to select the LineIn as the source of choice.
I recall having to install the whole Creative package just to get the LineIn activated on a SoundBlaster...
If you can get the LineIn 'live' there are some nice free recording programs such as CDex :^)