I have my scores in Sibelius 4, I keep the files in my computer and also the GPO Studio saved files. I just updated to GPO Studio v2, and the files are working fine.. I just want to know, if I update my computer with Sibelius 5, can I load the files saved with Sibelius 4 without problem? will it load the correct channels and all the stuff?
Yes, but there are a few things to take into account. First is that the whole playback engine is different - it uses Kontakt Player 2. This will allow you to use any VST. Read about this in the online pdf that comes with your installation.
After you have installed Sib 5, and have al the registration stuff out of the way, go to Devices, and activate a Kontakt Player; then choose the Soundset from the drop down list (there is one for GPO, JABB, etc). Then, open your score. In the Mixer (which has also changed) choose your playback device - in this case Kontakt Player 2 (you can name them, if you wish) for each instrument (sort of like choosing Garritan Studio in Sib 4). You are done.
There is more, and you may hit some problems, but they can be worked out, especially with the Sib board as a place to ask questions. It is a bit more confusing - at first - but it is much more flexible, and has soem real advantages and improvements.