Ubuntu: Samba installed by DEFAULT?

Hi,

1) I have successfully installed a linux client workstation (Ubuntu 10.04.3) in the enterprise environment
- It is the same as installing the windows XP client which gets  the IP address from DHCP server (we do not need to do a special configuration or setting for it)
- This linux client machine is in the production environment
- It can connect to Internet (ping www.yahoo.com, etc)
-By default, it uses the firefox web browser

2) This linux Ubuntu client machine has to be able to get some files at the FILE SERVERS which are in the Active Directory Environment; say it the name of the file server is BobaFilesrv

3) Per EE's discussion, I get to know that this Linux client machine should have SAMBA to function as mentioned in # 2 above

4) And, also per EE's discussion, that SAMBA will be installed by DEFAULT in the Ubuntu's installation

5) My questions:
First: is the statement # 4 above is CORRECT? (= SAMBA has been installed by DEFAULT; so I should not do anything related to Samba to achieve the goal --> the goal is to ACCESS the Bobafilesrv from Ubuntu client)

Second: How to check (in Ubuntu linux client) that SAMBA has been installed? (Please provide a little bit of steps)

6) Thanks

tjie