When a Win 7 machine cannot see other XP or WHS based machines all the usual Netbios TCP/IP, Homegroup turned off, and turning network discovery on is the first thing to do. If it still does not work then the real fix is likely what I found to be a registry entry that somehow gets a state change that causes the issue.
Registry Location:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Netbt\Parameters
Key: DhcpNodeType
Value Type: REG_DWORD - Number
Valid Range: 1,2,4,8 (B -node, P-node, M-node, H-node) Mine was at 2 which is wrong it needs to be 8
Default: 1 or 8 based on the WINS server configuration
Description: This optional parameter specifies the NBT node type. It is written by the DHCP client service, if enabled. This parameter determines what methods NetBT uses to register and resolve names. A B-node system uses broadcasts. A P -node system uses only point- to-point name queries to a name server (WINS). An M -node system broadcasts first, and then queries the name server. An H -node system queries the name server first, and then broadcasts. Resolution through LMHOSTS and/or DNS, if enabled, follows these methods. If this key is not present, the system defaults to B -node if there are no WINS servers configured for the network. The system defaults to H -node if there is at least one WINS server configured.