Samba Server Xp guest account issue

[fan0o]

Windows 7 users are accessing the share without any trouble but when i access it through windows XP pro services pack 2, the following dialog box shows up
i did add guest ok = yes in conf file but didn't work for me

# Samba config file created using SWAT
# from UNKNOWN (192.168.1.1)
# Date: 2011/02/25 15:05:29

[global]
	workgroup = SDSOLTECH
	server string = Samba Server Version %v
	security = SHARE
	log file = /var/log/samba/log.%m
	max log size = 50
	cups options = raw

[homes]
	comment = Home Directories
	read only = No
	browseable = No

[printers]
	comment = All Printers
	path = /var/spool/samba
	printable = Yes
	browseable = No

[Share]
	path = /var/www/html/
	writeable= Yes
	create mode = 0770
	directory mode = 0770
	share modes = Yes
	guest ok  = No
	valid users = @security

Regards and thanks