Windows 7: Having trouble with W7 & XP home network setup

Trying to setup home network with same machines but with 2 of the desktops recently upgraded to Windows 7 Pro. Here's the breakdown:

2 Desktops running new Windows 7 Pro systems - (hardwired)
1 Desktop running XP Pro SP3 - (hardwired)
2 laptops running XP Home Ed SP3 (Wireless)

Attached is a shot of what the main desktop (Home_Desktop Windows 7 Pro) finds in Networks (allnetworks.jpg):

Home_Desktop finds all but one laptop (RoadWorrior) but... will not connect to Lower_Office...I get the attached error window (network.jpg)

No issues connecting to MaryAnn-PC (Win 7 Pro SP3) and/or Maryannslaptop (XP HE SP3)

However...from Lower_Office XP Pro desktop...I can connect and move files back and forth from Home_Desktop...?...but can not connect from Home_Desktop to Lower_office as network.jpg indicates ?

The laptop (RoadWarrior) will not connect or be found either..but want to concentrate on above desktop issue first.

Here's ipcongif /all on problem machines:

Microsoft Windows XP [Version 5.1.2600]
(C) Copyright 1985-2001 Microsoft Corp.
C:\Documents and Settings\Tim>ipconfig /all
Windows IP Configuration
Host Name . . . . . . . . . . . . : LOWER_OFFICE
Primary Dns Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Unknown
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No
Ethernet adapter Local Area Connection:
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : NVIDIA nForce 10/100/1000 Mbps Ether
net
Physical Address. . . . . . . . . : 00-15-58-69-CA-D9
Dhcp Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
IP Address. . . . . . . . . . . . : 192.168.0.2
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 192.168.0.1
DHCP Server . . . . . . . . . . . : 192.168.0.1
DNS Servers . . . . . . . . . . . : 192.168.0.1
Lease Obtained. . . . . . . . . . : Wednesday, March 10, 2010 9:51:36 AM
Lease Expires . . . . . . . . . . : Thursday, March 11, 2010 9:47:45 AM
C:\Documents and Settings\Tim>

********************************************************************************************

Microsoft Windows [Version 6.1.7600]
Copyright (c) 2009 Microsoft Corporation. All rights reserved.

C:\Users\Tim>ipconfig /all
Windows IP Configuration
Host Name . . . . . . . . . . . . : Home_Desktop
Primary Dns Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Hybrid
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No
Ethernet adapter Local Area Connection:
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Realtek PCIe GBE Family Controller
Physical Address. . . . . . . . . : 90-E6-BA-54-94-87
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
Link-local IPv6 Address . . . . . : fe80::b55c:4e1e:d47e:ecf5%11(Preferred)
IPv4 Address. . . . . . . . . . . : 192.168.0.4(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Lease Obtained. . . . . . . . . . : Wednesday, March 10, 2010 9:59:49 AM
Lease Expires . . . . . . . . . . : Thursday, March 11, 2010 9:59:48 AM
Default Gateway . . . . . . . . . : 192.168.0.1
DHCP Server . . . . . . . . . . . : 192.168.0.1
DHCPv6 IAID . . . . . . . . . . . : 244377274
DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-12-EC-16-29-90-E6-BA-54-94-87
DNS Servers . . . . . . . . . . . : 192.168.0.1
NetBIOS over Tcpip. . . . . . . . : Enabled
Tunnel adapter isatap.{78E58B9A-43A9-47D9-A48D-A5FB5F486411}:
Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Microsoft ISATAP Adapter
Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes
Tunnel adapter Local Area Connection* 9:
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Teredo Tunneling Pseudo-Interface
Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes
IPv6 Address. . . . . . . . . . . : 2001:0:4137:9e76:2ca6:2f70:3f57:fffb(Pref
erred)
Link-local IPv6 Address . . . . . : fe80::2ca6:2f70:3f57:fffb%13(Preferred)
Default Gateway . . . . . . . . . : ::
NetBIOS over Tcpip. . . . . . . . : Disabled
C:\Users\Tim>

Thanks..

Thanks guys...couple more questions before I go to far with this....

1) Everything now is wep....do I have to remove all wep info (keys) etc from all computers/printers, etc before I switch the router over to WPA ?

2) When editing the registry to disable IPv6 which number option should I use ?

From link How to disable certain Internet Protocol version 6 (IPv6) components in Windows Vista, Windows 7 and Windows Server 2008

5. Type any one of the following values to configure the IPv6 protocol, and then click OK:
1. Type 0 to enable all IPv6 components.

Note The value "0" is the default setting.
2. Type 0xffffffff to disable all IPv6 components, except the IPv6 loopback interface. This value also configures Windows Vista to use Internet Protocol version 4 (IPv4) instead of IPv6 in prefix policies.
3. Type 0x20 to use IPv4 instead of IPv6 in prefix policies.
4. Type 0x10 to disable native IPv6 interfaces.
5. Type 0x01 to disable all tunnel IPv6 interfaces.
6. Type 0x11 to disable all IPv6 interfaces except for the IPv6 loopback interface.

Note You must restart your computer for these changes to take affect.

3) After modifying registry...my network icon in system tray now has a yellow exclamation over it ? Is this correct ?

As I said...I hadn't done anything with Homegroup since installation as the attached jpg shows....?...I don't understand why the one XP laptop networks fine with Win 7 machines...but the other two don't ?

TR