How can I share file and printers in Windows XP Professional?

I added the following items to all connections and I still can't
connect to one computer when I typing \\computer_name (or \\IP) in
another computer:
client for networks
file and printers sharing
qos packet schedulers
nwlink netbios
nwlink IPX/IPX/netbios
Internet Protocol(TCP/IP)

BTW the network between the computers works properly.

I hope that somebody can help me,
Thanks.