They Trying To Login To My Win2003 Server

Running A Windows 2003 Server at co-location. I just looked at my event viewer security log and am stunned to see thousands of Failure Audit logon attempts. They have been trying since Saturday at 9:43pm, till currently. Almost all of them failed, but a few were successfull. All of the successfull attempt appear to be:

Successful Network Logon:
User Name:
Domain:
Logon ID: (0x0,0x2E9F395)
Logon Type: 3
Logon Process: NtLmSsp
Authentication Package: NTLM
Workstation Name: DAS
Logon GUID: -
Caller User Name: -
Caller Domain: -
Caller Logon ID: -
Caller Process ID: -
Transited Services: -
Source Network Address: 125.82.7.86
Source Port: 0

How do I lock this down? How can I block these guys from trying to login? The IPS are coming from all over the world though. I did whois for a few, and they range from Poland, Russia, to China.