help with Media player/iPod/syncing.

If I sync songs onto my ipod using Media Player, will the songs that are already on my iPod go away/get replaced?

Okay, I used to use iTunes on my laptop to upload songs on my iPod, but my laptop broke. Which means all the songs on the laptop are gone and I can't upload them onto my iPod ever again.
on my family computer, I have about 100 songs on media player. I wanna upload that on my iPod, but I'm scared it my erase the ones I already have.

so yeah, will it erase the ones I already have on my iPod if I sync some songs on it with Media Player?

Someone please tell me. =(