Windows SharePoint Services v3.0 and Microsoft Office SharePoint Server 2007
maybe you still wonder "WSS 3 and MOSS 2007, waht's the different ?"
1. Major Different
first, MOSS 2007 is build on the top of WSS v3
2. Pricing
WSS v3 is free, but not MOSS 2007
for more detail about Pricing :
http://office.microsoft.com/en-us/sharepointserver/FX102176831033.aspx
3. Feature
more detail :
http://dotnetaddict.dotnetdevelopersjournal.com/moss_vs_wss.htm