You have a problem with name resolution on the client you try to connect from (W7).
All connections are made to a destination IP address. If you supply a name, the computer first resolves that name into an IP address. This is where you fail today.
If your gentoo box / home router's IP address can't be looked up from either the hosts file, or with an A (or AAAA for IPv6) record in DNS (possibly via a CNAME), your windows machine won't understand what IP the gentoo box has.
To be able to give a good answer to your question, we need a bit more information from you, describing the network setup a bit, so we don't make wrong guesses.
For instance:
- are the windows and gentoo boxes both on the "inside" network?
- are they both configured as DHCP clients?
- is the router the only DHCP server on the internal network?
Did you use any DynDNS service when it was working earlier, or has the W7 installation changed somehow? (Different PC, reinstall, virus, etc?) Perhaps you had an entry in the hosts file before, when it was working, and it is now missing.
Why the router can figure out the internal/private IP address of the linux box while the windows box cannot, is because they use different sources for their name information. Maybe the router itself has that information. Is it also a DHCP server? Maybe that's why the router knows.
EDIT (2012-08-06):
Based on new input,
On the gentoo box, make sure you have an entry in /etc/hosts that looks like this:
192.168.0.3 hostname.domain.tld hostname
(replace 192.168.0.3 with the real (internal) IP address of the gentoo server, and hostname.domain.tld to be the fully qualified domain name you wish to use, and the last word on the line to be the hostname without the domain (ie, the word before the first .).
Put the same line in the %WINDIR%\System32\drivers\etc\hosts file, but remember that windows name lookups of your gentoo box will be then taken from that file, and not from DNS.
This should make the name lookups work (locally) on both the gentoo server itself, and the windows client, without consulting DNS.
In /etc/apache2/vhosts.d/00_default_vhost.conf (if that's where your web server is configured), make the ServerName entry match the FQDN (hostname.domain.tld) that you have in the /etc/hosts file.
This should allow apache to start without warnings.
Best Answer
Windows uses DNS to resolve FQDN names - host1.contoso.com for example.
In your case, whitey is the NetBIOS name and DNS have no (and shouldn't have) knowledge of it.
I'm not a Linux expert, but as far as I know your Linux server needs Samba in order to be able to broadcast its NetBIOS name across Windows machines.