You neglect to mention exactly what you need to accomplish this "Windows Networking integration" beyond specifying a workgroup.
For secure, password-protected shares, and to specify a particular workgroup, you need to configure your
You can use swat (Samba Web Administration Tool, available in Karmic's
universe repository); it's an older package but should still work. Typically, once SWAT is installed and running, you use it by browsing to
You can also use Webmin; install it via the .deb package on the Webmin download page. Have a look at the Webmin Samba HOW-TO for specifics. Either of these tools will provide web-based configuration for Samba; Webmin configures many other services as well.
Read through Ubuntu's Setting Up Samba page for more info. You can configure very simple shares directly in Gnome, as matpol's answer suggests -- use Gnome's "Places" menu to connect to shares from other computers. You can also create shares by browsing to them in the filemanager and selecting "Share Folder" in the right-click menu. If you don't have the Samba server installed, you'll get a popup that tells you "Sharing services are not installed". Select the SMB option, deselect NFS, and then click "Install Services". This will install the samba and smbfs packages for you, and then create a basic, browsable, public share on the folder you've shared.