I am pretty sure you will lose your music . . . I have had issues like this in the past . . . . what I recommend is . . . don't just put it on an iPod, but try to download it all on CD's then you will have a hard copy of all the music . . . . I know that may be very cumbersome, but it is the only guaranteed way in my opinion that you will have all your music . . . .
Uninstall and reinstall iTunes will not affected your iTunes library which are stored at a different location. Once new iTunes is installed, it will search the default locationb to look for your library file.
iTunes Library Folder(including your purchased media) locations:
C:\Documents and Settings\username\My Documents\My Music\iTunes
C: \Users\username\My Music\iTunes
However, it's always advisable to do a backup of this iTunes folder in case something happened.