XP home cannot connect to sql server

hi
i have 2 laptops both using XP home (one is SP2 and one is SP3) both of them cannot connect to my MS sql server 2005 over the internet, i have XP pro sp3 which connects seamlessly and so do my 2 other vista home basic machines.

i get the error that server doesnt exist or access denied on the xp home machines.. i have pretty much tried everything .. please help ??