Many users are complaining about getting one of these errors when installing MSN Messenger 6. To help tidy up the constant onslaught of repeat questions, I am going to post the suggestions made so far here, and links to helpful posts. All other unanswered/unhelpful posts regarding these errors will be locked/deleted/pointed here. OK on with the solutions:
Before you do anything, make sure you have the latest version of MSN Messenger installed from http://messenger.msn.com/ and your system has all necessary updates from http://windowsupdate.microsoft.com/
1603 Fix - courtesy of Christianbest
1. Find C:\WINDOWS\WinSxS
2. Rename the folder "InstallTemp" to "InstallTemp2".
3. Then Rename the file "x86_Microsoft.Windows.Networking.Dxmrtp_6595b6414 4ccf1df_5.2.0.4868_x-ww_212f7d9e" to "x86_Microsoft.Windows.Networking.Dxmrtp_6595b6414 4ccf1df_5.2.0.4868_x-ww_212f7d9e2".
4.Or simply take the folder and the file and add a 2, that way it will replace with a new one.
5. Install away!
More Information - How to fix "1603" HERE!
Another Possible Fix for 1603
1. Click on Start -> Find -> Files or Folders
2. Search for sfc.dll. It should be under c:\windows\system32\.
3. Rename sfc.dll to sfc.dll.x [x could be any character(s)]
4. You should be able to do the installs now.
5. After you have installed the software, change sfc.dll.x back to
sfc.dll.
6. Done!
1601 Fix - courtesy of naRc
1. Click START, and then click RUN.
2. In the OPEN box, Type msiexec /unreg, and then click OK
3. When this process is complete, click START, and then click RUN.
4. In the OPEN box, type msiexec /regserver, and then click OK.
5. Now install MSN 6.
More Information - Help Installing MSN 6 preview
Another Possible Fix for 1601 - courtesy of DrDeo
1. Open a command prompt. (Start ->Run-> type "CMD.EXE" or "command"

2. Type msiexec /unregister and press Enter.
3. Type msiexec /regserver and press Enter.
zar je ovo bilo tesko
http://www.google.ba/search?hl=bs&q=msn+1603+error&meta=&btnG=Google+pretraga