I apologize if this has already been covered or if it is in the wrong spot, but after much research I am finally able to connect to my work computer on Win2k again. For a long time I could only connect as a guest. I came across this article that proved to be VERY helpful. I thought someone might benefit from it:

Guest Issues
1.If you connect as GUEST and you have rename your Pocket PC, you need to perform a soft reset for the new name to take effect. See Microsoft Article Q259954 for details.

2.If you connect as GUEST to your Pocket PC and you are using ActiveSync
3.x, you may need to re-register the Microsoft XML DLLs. To register the DLL, issue the command "\WINDOWS\SYSTEM32\REGSVR32 MSXML3.DLL" or "\WINNT\SYSTEM32\REGSVR32 MSXML.DLL" and "\WINDOWS\SYSTEM32\REGSVR32 MSXML3.DLL" or "\WINNT\SYSTEM32\REGSVR32 MSXML.DLL" Do not type the quotes with the command. This re-registers the DLL with Windows. Then reboot your PC before trying to synchronize again.

3.If you connect as GUEST, then click the start button and select the “run” option and type “syncmgr /quit”. Then turn off your Pocket PC and turn it on again.

4. If you are connecting as GUEST, try reinstalling Internet Explorer 6 (except XP users). This has fixed the GUEST synchronization problem for other users. For Windows XP users you can repair Internet Explorer by following Microsoft's KB Article 318378.

5. If you are connecting as GUEST with Windows 2000? You need to have read-write access to the ActiveSync program folder and subfolder to create a partnership. See Microsoft's KB Article 259875.
6. Intermittent guest connections if the user has Synchrologic mail syncing program is installed on their Pocket PC with less than 64MB of ram. Contact Synchrologic for an update.

7. If you are using a firewall and you do not allow Port 990 to be used by ActiveSync you will connect as a Guest. For a comprehensive list of ports that ActiveSync uses please read the Protocols FAQ.

8. Check and see of the registration key at HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows CE Services and see whether a key named GuestOnly has a value of 1. If it does then change the value to 0 to allow you to setup a partnership. An alternative is to use a free application called ActiveSync Keys which is available at Undocumented ActiveSync Keys. NOTE: Microsoft does not support end users editing the registry so there is no support for performing this.

9. If you have McAfee Virusscan Enterprise version 7.1.0 installed before you install ActiveSync, you will be able to sync only once as a guest. To resolve this problem, uninstall McAfee, install ActiveSync and then reinstall McAfee. If your problem is not resolved here, try the Microsoft's Knowledge Base search on ActiveSync or Microsoft's Knowledge Base search on Mobile Information Server

Thanks to Chris De Herrera's Windows CE Website for this info.