Cannot join Windows 7 64 bits to SBS 2003 domain

You need to have SBS full patched, i.e. up to date.
Then make sure DNS points ONLY to the SBS, and if there is more than one network adapter such as a wired and wireless adapter, disable all but the wireless adapter. You should be then be able to joint the domain with the   http://SBSname/connectcomputer wizard. Once complete you can re-enable other network adapters and they will work fine.
Where 32 bit WINS worked I suspect it is due to multiple NIC's.

Hello,
I have just the Local area connection enabled, wireless disabled. I went to the Properties of Internet Protocol Version 4 and changed to use the following DNS server addresses to point to my SBS server and I get the same error. It looks like it is going to work and even creates the _sbs_netsetup_ user but it just doesn't finish. I just get the same error.

Have you installed the following updates:
http://support.microsoft.com/kb/926505
When you configured DNS, make sure you didn't just add the SBS, it must point only to the SBS and not an ISP or router, even as an alternate.

Do you have DNS server configured properly? Enter command prompt and type nslookup - does your server respond without errors? Can you ping your domain controler by domain, e.g. ping mydomain.local ?
Also, I read your question: "and compared the TCP/IP properties of both computers and they look the same" - I hope they does not look exactly the same :) I mean IP address is different?

Yes I installed the update for kb 926505 but I couldn't install the ISA server SP3 that was suggested on the website because I get the error mentioned on the original post. I entered nslookup on the command prompt of the Win7 machine and I get:
Default server: server.mydomain.local
Then I clicked exit and typed: ping server.mydomain.local and I got 4 replies with 0 lost.
But I keep getting the same error

Could you please post here ipconfig /all of your server and those two Windows 7 computers?

Here is for the Windows 7 64 bits:
C:\Users\User>ipconfig /all

Windows IP Configuration

   Host Name . . . . . . . . . . . . : User-PC
   Primary Dns Suffix  . . . . . . . :
   Node Type . . . . . . . . . . . . : Broadcast
   IP Routing Enabled. . . . . . . . : No
   WINS Proxy Enabled. . . . . . . . : No
   DNS Suffix Search List. . . . . . : LoneStarMilkProducers.local

Ethernet adapter Local Area Connection:

   Connection-specific DNS Suffix  . : LoneStarMilkProducers.local
   Description . . . . . . . . . . . : Intel(R) 82567LM Gigabit Network Connecti
on
   Physical Address. . . . . . . . . : 00-24-E8-FA-AE-14
   DHCP Enabled. . . . . . . . . . . : Yes
   Autoconfiguration Enabled . . . . : Yes
   Link-local IPv6 Address . . . . . : fe80::f083:c096:e438:c7dd%11(Preferred)
   IPv4 Address. . . . . . . . . . . : 192.168.16.30(Preferred)
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Lease Obtained. . . . . . . . . . : Monday, December 28, 2009 12:25:34 PM
   Lease Expires . . . . . . . . . . : Tuesday, January 05, 2010 2:08:31 PM
   Default Gateway . . . . . . . . . : 192.168.16.2
   DHCP Server . . . . . . . . . . . : 192.168.16.2
   DHCPv6 IAID . . . . . . . . . . . : 234890472
   DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-12-BC-15-86-00-24-E8-FA-AE-14

   DNS Servers . . . . . . . . . . . : 192.168.16.2
   Primary WINS Server . . . . . . . : 192.168.16.2
   NetBIOS over Tcpip. . . . . . . . : Enabled

Tunnel adapter isatap.LoneStarMilkProducers.local:

   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

And here is for the server:

Microsoft Windows [Version 5.2.3790]
(C) Copyright 1985-2003 Microsoft Corp.

C:\Documents and Settings\Administrator>ipconfig /all

Windows IP Configuration

   Host Name . . . . . . . . . . . . : lsmserver
   Primary Dns Suffix  . . . . . . . : LoneStarMilkProducers.local
   Node Type . . . . . . . . . . . . : Unknown
   IP Routing Enabled. . . . . . . . : Yes
   WINS Proxy Enabled. . . . . . . . : Yes
   DNS Suffix Search List. . . . . . : LoneStarMilkProducers.local

Ethernet adapter Network Connection:

   Connection-specific DNS Suffix  . :
   Description . . . . . . . . . . . : Intel(R) PRO/1000 MT Network Connection #
2
   Physical Address. . . . . . . . . : 00-13-72-F6-2C-03
   DHCP Enabled. . . . . . . . . . . : No
   IP Address. . . . . . . . . . . . : 204.118.30.95
   Subnet Mask . . . . . . . . . . . : 255.255.255.192
   Default Gateway . . . . . . . . . : 204.118.30.65
   DNS Servers . . . . . . . . . . . : 192.168.16.2
   Primary WINS Server . . . . . . . : 192.168.16.2
   NetBIOS over Tcpip. . . . . . . . : Disabled

Ethernet adapter Server Local Area Connection:

   Connection-specific DNS Suffix  . :
   Description . . . . . . . . . . . : Intel(R) PRO/1000 MT Network Connection
   Physical Address. . . . . . . . . : 00-13-72-F6-2C-02
   DHCP Enabled. . . . . . . . . . . : No
   IP Address. . . . . . . . . . . . : 192.168.16.2
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Default Gateway . . . . . . . . . :
   DNS Servers . . . . . . . . . . . : 192.168.16.2
   Primary WINS Server . . . . . . . : 192.168.16.2

PPP adapter RAS Server (Dial In) Interface:

   Connection-specific DNS Suffix  . :
   Description . . . . . . . . . . . : WAN (PPP/SLIP) Interface
   Physical Address. . . . . . . . . : 00-53-45-00-00-00
   DHCP Enabled. . . . . . . . . . . : No
   IP Address. . . . . . . . . . . . : 192.168.16.26
   Subnet Mask . . . . . . . . . . . : 255.255.255.255
   Default Gateway . . . . . . . . . :
   NetBIOS over Tcpip. . . . . . . . : Disabled

Your network configuration seems to be ok, you should be able to join domain if AD and DNS works correctly.
Now try to go to Win7 64 computers system properties (control panel->system->change settings of computer name, domain etc) and try to swith from workgroup to domain LoneStarMilkProducers.local - does it prompt for administrators credentials?
Make sure that there is no computer in AD with same computer name.

I changed the domain and first I got a window saying welcome to the domain but then I got an error:
Computer Name/Domain Changes
Changing the Primary Domain DNS name of this computer to "" failed. The name will remain "LoneStarMilkProducers.local"
The error was:
The remote procedure call failed and did not execute

Any ideas?

You were right the problem was ISA server after I followed your steps I was able to join the computer without any problems. I am still wondering why this is just a problem with 64 bits, but anyway it is working.
Thank you very much for all your help