what the hell is _netdev?
try removing that option unless you know better.
also for names to work in fstab like this one:
tryggve:/mnt/140g /mnt/net/140g nfs defaults 0 0
you need a line in the /etc/hosts file for each one like so:
10.3.0.1 tryggve try router
alternatively there is a dns server in your network which knows where "server1" is.
your distro probably has an init script called something like nfsmount in /etc/init.d or /etc/rc.*
make sure it is included in the startup configuration