Snow Leopard upgrad from OSX10.5.8 with Paralells 4

I currently have a late summer 2009 Macbook Pro with OSX 10.5.8 running Parallels 4 W/ Win XP Pro. If I install Snow Leopard as an upgrade, will I lose any functionality of my Parallels VM?? Will I have to reload Windows etc? Any insights would be appreciated. Thanks!