If you have a Virtual Box WIndows server and you want to connect to it from the Solaris server it is running on..try this
1. Set the Virtual Box to DHCP and you will probably find you can ping the Solaris server and back again
2. Get up a command prompt and do IPCONFIG
3. Set up your static IP address and make sure you set up the WINS SERVER and TURN ON NETBIOS
TADA!